EP0800529A1

EP0800529A1 - Peptides and synthetic cell membranes

Info

Publication number: EP0800529A1
Application number: EP95941036A
Authority: EP
Inventors: Renate Naumann; Alfred Jonczyk
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 1994-12-16
Filing date: 1995-11-29
Publication date: 1997-10-15
Also published as: AU4257596A; JPH10510277A; US5962638A; DE4444893A1; WO1996018645A1

Abstract

The invention concerns linear peptides of formula (I) R-A-B-C-D-E-OH, wherein R, A, B, C, D and E have the meanings indicated; the production of said linear peptides; and their use as biosensors, solar cells and membrane models for use in the investigation of biochemical processes.

Description

Peptides and synthetic cell membranes

The invention relates to peptides or peptide-analogous compounds of the formula I.

R-A-B-C-D-E-OH I,

wherein

A an amino acid residue selected from a group consisting of Ala, Gly or Leu,

B an amino acid or dipeptide residue selected from one

Group consisting of Ala, Ser, Gly-Gly and Ser-Ser,

C an amino acid, di or tripeptide residue selected from a group consisting of Ala, Ala-Ala, Leu-Leu, Ala-Ala-Ala, Arg-Gly-Asp and Leu-Leu Leu,

D an amino acid residue selected from a group consisting of Ala and Ser,

E is an amino acid or dipeptide residue selected from one

Group consisting of Ala, Leu and Pro-Lys,

R H, HS-alkyl-CO-, HS-alkyl-CO-NH-alkyf-CO-, Trt-S-alkyl-

CO-, Trt-S-alkyl-CO-NH-alkyl'-CO- or 1,2-dithiocyclopentane-3- (CH2) -rCO-, where R can only be H if at least one of the radicals A , B, C, D or E is not equal to Ala,

alkyl and alkyl 'each independently of one another an alkylene radical having 1 to 11 carbon atoms

and Trt triphenylmethyl

mean,

as well as their salts.

Lipids and proteins are the main components of biological membranes. Lipid bilayers are considered models of cell membranes. Peptides or proteins can be embedded in such lipid bilayers so that they span them by inserting perpendicular to the surface (JC Huschilt et al. BBA 979, 139-141 (1989)). The conformation of such a double layer is determined by the sequence of the peptide. JD Leer et al. (Science 240, 1177-1181 (1988)) that the peptide H- (Leu-Ser-Ser-Leu-Leu-Ser-Leu) ₃ -CONH ₂ with a membrane-spanning length as an amphiphilic alpha helix forms an ion channel , which arises from self-organization of these helices in bundles. A peptide of this sequence consisting of 14 amino acids, which is too short for straining the lipid bilayer, could not form this discrete channel. The peptide H- (Leu-Ser-Leu-Lθu-Leu-Ser-Leu) 3-CONH _2, however, forms a proton channel.

Omega-substituted alkane thiols bind and organize on gold surfaces (CD. Bain et al., Angew. Chemie 101, 522-528 (1989)).

Alkanthiols (octanethiol and hexadecanethiol) form an organized monolayer on gold-coated electrodes, on which lipid bilayers can be formed with lipids. The adsorption of proteins (cholera toxin) onto the monolayer can be analyzed electrochemically (impedance measurement) and optically (surface plasmon resonance). The electrochemical measurement leads to statements about the quality of the layer and about the amount of ligand molecule inserted. The optical method allows the quantification of the gold-bound amount of lipid and the selective binding of the acceptor molecule (cholera toxin) to the membrane (S. Terrettaz et al. Langmuir 9, 1361-1369 (1993)). The interaction of surface-bound anti-mouse IgG antibodies with mouse IgG as ligand was measured not on gold but on tantalum / tantalum oxide. The change in impedance of this immunochemical reaction was analyzed in real time in a flow cell. The protein was not anchored via a thiol, but bound via an aminoalkylsilane (A. Gebbert et al. Anal. Che. 64, 997-1003 (1992)).

Spherical particles made of polymethyl methacrylate could be coated with H- (Ala) ₅ -OMe using a carbodiimide. After hydrolysis of the esters, the lipid phosphatidylethanolamine could be coupled to the carboxyl functions of the peptides. Adsorption of further phospholipids allowed lipid bilayers to be formed, into which bacteriorhodopsin was incorporated. By determining the direction of the proton pumps produced and electron microscopy it could be shown that the preferred orientation of the bacteriorhodopsin in the lipid layer runs from the inside out (U. Rothe et al. FEBS Lett. 263, 308-312 (1990)).

The invention was based on the task of finding new compounds with valuable properties, in particular those which can be used for the production of peptide layers, peptide-analog layers or of cell membranes.

It has been found that mercaptoalkylcarboxy peptides of the formula I are bound to gold surfaces and that they organize themselves into dense layers, especially if lipids (eg dimyristoyl-phosphatidyl-oxyethylamine, DMPE) are covalently attached to the peptidyl-gold phase be coupled.

This creates monomolecular lipid layers on the gold surface, which are covalently bound to the gold via the peptide spacer group. Alternatively, lipid layers can also be applied to the peptide layer using the Langmuir-Blodgett technique. The method is described, for example, by G. Puu, I. Gustavson, P.-A. Ohlsson, G. Olofson and A. Sellstram in Progress in Membrane Biotechnologie p. 279 ff. (1991),

Birkhäuser Verlag, Basel (Eds. Fernandez / Chapman / Packer). The peptide spacer is used to form a hydrophilic layer between the hydrophobic lipid layer and the gold electrode. The lipid monolayer formed in this way can be provided, for example, with the aid of the Langmuir-Blodgett technique or by rolling out liposomes with a second lipid layer, so that defined lipid bilayers are formed which represent a model of a biological membrane in that they adjoin a water phase on both sides . They are able to insert functional membrane proteins and thus allow their electrical, structural and binding properties to be investigated.

These lipid-peptide-gold constructs are therefore capable of forming double layers and inserting proteins. The formation and order status of the layers can be measured using cyclic voltammetry, impedance spectrometry and surface plasmon resonance spectroscopy (SPRS).

The compounds of the formula I can be used as building blocks for synthetic peptide layers or biological membranes, in particular cell membranes.

The abbreviations of amino acid residues listed above and below stand for the residues of the following amino acids:

Ala Alanine Arg Arginine

Asp aspartic acid

Cys cysteine

Gly glycine

Leu Leucine Lys Lysine

Per proline

Ser Serin. Also mean below:

BOC tert-butoxycarbonyl

CBZ benzyloxycarbonyl

DCCI dicyclohexylcarbodiimide

DIC Di isopropy learbodii with id

DMF dimethylformamide

DMPE dimyristoylphosphatidylethanolamine

EDCI N-ethyl-N '- (3-dimethylaminopropyl) carbodiimide hydrochloride

Et ethyl

Fmoc 9-fluorenylmethoxycarbonyl

HOBt 1 -hydroxybenzotriazole

Me methyl

MBHA 4-methyl-benzhydrylamine

Mtr 4-methoxy-2,3,6-trimethylphenyl sulfonyl

OBut tert-butyl ester

OMe methyl ester

OEt ethyl ester

POA phenoxyacetyl

TFA trifluoroacetic acid

Trt trityl (triphenylmethyl).

If the above-mentioned amino acids or residues can occur in several enantiomeric forms, then above and below, e.g. as a constituent of the compounds of the formula I, including all of these forms and also their mixtures (for example the DL forms). Furthermore, the amino acids or the amino acid residues can be derivatized in a form known per se.

The invention further relates to a process for the preparation of a compound of the formula I according to Claim 1 or one of its salts, characterized in that it is liberated from one of its functional derivatives by treatment with a solvolysing or hydrogenolysing agent, or that a peptide of formula II

M-OH II

wherein

M R, but not hydrogen, R-A, R-A-B, R-A-Gly, R-A-B-C,

R-A-B-Leu, R-A-B-Arg, R-A-B-Arg-Gly or R-A-B-C-D

means

with an amino compound of formula III

H-Q-OH III

wherein

Q E, Lys, D-E, C-D-E, Leu-D-E, Asp-D-E, Gly-Asp-D-E,

B-C-D-E, Gly-C-D-E, A-B-C-D-E or NH-alkyl'-CO-A-B-C-D-E

means

implements

and / or that one optionally acylates a free amino group and / or converts a compound of the formula I into one of its salts by treatment with an acid or a base.

Above and below, the radicals A, B, C, D, E and R have those in the

Formulas I, II and III meanings, unless expressly stated otherwise.

In the above formulas, alkyl and alkyl 'independently of one another are preferably -CH ₂ -, - (CH ₂ ) ₂ -, - (CH ₂ ) ₃ -, - (CH ₂ ) ₄ -, - (CH ₂ ) ₅ -, - (CH ₂ ) ₉ -, - (CH ₂ ) ₁₀ - or - (CH ₂ ) _ι . R preferably denotes Trt-S-alkyl-CO-, HS-alkyl-CO-, Trt-S-alkyl-CO-NH-alkyl'-CO-, HS-alkyl-CO-NH-alkyl'-CO- or 5 - (1,2-dithiocyclopentan- 3-yl) pentanoyl-.

Group A is preferably Ala or Gly. B is preferably Ser or

Ser-Ser but also Ala or Gly-Gly. C is preferably Ala, Ala-Ala or Arg-Gly-Asp. E is preferably Ala or Pro-Lys.

Accordingly, the invention relates in particular to those compounds of the formula I in which at least one of the radicals mentioned has one of the preferred meanings indicated above.

A preferred group of compounds can be expressed by the formula Ia, which corresponds to the formula I and in which B, C, E, X and Z have the meanings given there and

A Ala, B Ala or Ser-Ser,

E mean Ala or Pro-Lys.

Another group of preferred compounds can be expressed by the sub-formulas laa to lad, which otherwise correspond to the formulas I and la, but additionally

in laa: R HS-alkyl-CO- in lab: R Trt-S-alkyl-CO- in lac: R Trt-S-alkyl-CO-NH-alkyl'-CO in lad: R HS-alkyl-CO- NH-alkyl'-CO-

mean. Particularly suitable compounds of the formula I are:

(a) Trt-S- (CH ₂ ) ₂ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH;

(b) HS- (CH ₂ ) ₂ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH; (c) Trt-S- (CH ₂ ) ₂ -CO-Ala-Ala-Ala-Ala-Ala-OH;

(d) HS- (CH ₂ ) ₂ -CO-Ala-Ala-Ala-Ala-Ala-OH;

(e) 5- (1,2-dithiocyclopentan-3-yl) pentanoyl-Ala-Ala-Ala-Ala-Ala-OH;

(f) Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH; (g) HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH;

as well as their salts.

The compounds of formula I and also the starting materials for their

Manufacture are otherwise produced by known methods as described in the literature (for example in the standard works such as Houben-Weyl, methods of organic chemistry, Georg-Thieme-Veriag, Stuttgart), and under reaction conditions necessary for the reactions mentioned are known and suitable. It is also possible to use known variants which are not mentioned here in detail.

If desired, the starting materials can also be formed in situ, so that they are not isolated from the reaction mixture, but instead are immediately reacted further to give the compounds of the formula I.

The compounds of the formula I can be obtained by liberating them from their functional derivatives by solvolysis, in particular hydrolysis, or by hydrogenolysis.

Preferred starting materials for solvolysis or hydrogenolysis are those which, instead of one or more free amino and / or hydroxyl groups, contain corresponding protected amino and / or hydroxyl groups, preferably those which instead of an H atom which is associated with a N atom is connected, carry an amino protective group, for example those which correspond to the formula I, but instead of an NH ₂ group contain an NHR 'group (in which R' is an amino protective group, for example BOC or CBZ).

Preference is also given to starting materials which carry a hydroxyl protective group instead of the H atom of a hydroxyl group, e.g. those which correspond to the formula I, but instead of a hydroxyphenyl group contain an R "0-phenyl group (in which R" denotes a hydroxy protective group).

Several - identical or different - protected amino and / or hydroxy groups can also be present in the molecule of the starting material. If the existing protective groups are different from one another, they can in many cases be split off selectively.

The term "amino protecting group" is generally known and refers to groups which are suitable for protecting (blocking) an amino group from chemical reactions, but which are easily removable after the desired chemical reaction at other points on the mole ¬ küls has been carried out. Unsubstituted or substituted acyl, aryl, aralkoxymethyl or aralkyl groups are typical of such groups. Since the amino protective groups are removed after the desired reaction (or reaction sequence), their type and size is otherwise not critical; however, preference is given to those having 1-20, in particular 1-8, carbon atoms. The term "acyl group" is to be understood in the broadest sense in connection with the present process and the present compounds. It encompasses acyl groups derived from aliphatic, araiphatic, aromatic or heterocyclic carboxylic acids or sulfonic acids, and in particular alkoxycarbonyl, aryloxycarbonyl and especially aralkoxycarbonyl groups. Examples of such acyl groups are alkanoyl such as acetyl, propionyl, butyryl; Aralkanoyl such as phenylacetyl; Aroyl such as benzoyl or toluyl; Aryloxy alkanoyl such as POA; Alkoxycarbonyl such as methoxycarbonyl, ethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, BOC, 2-iodoethoxycarbonyl; Aralkyloxycarbonyl such as CBZ ("carbobenzoxy"), 4-methoxybenzyloxycarbonyl, Fmoc; Arylsulfonyl such as Mtr. Preferred amino protecting groups are BOC and Mtr.

The term "hydroxyl protecting group" is also generally known and refers to groups which are suitable for protecting a hydroxyl group against chemical reactions, but which are easily removable after the desired chemical reaction has been carried out elsewhere in the molecule. Typical of such groups are the abovementioned unsubstituted or substituted aryl, aralkyl or

Acyl groups, also alkyl groups. The nature and size of the hydroxyl protective groups is not critical since they are removed again after the desired chemical reaction or reaction sequence; groups with 1-20, in particular 1-10, carbon atoms are preferred. Examples of hydroxy protecting groups include Benzyl, p-nitrobenzoyl, p-toluenesulfonyl and acetyl, with benzyl and acetyl being particularly preferred. The COOH groups in aspartic acid and glutamic acid are preferably protected in the form of their tert-butyl esters (e.g. Asp (OBut)).

The functional derivatives of the compounds of the formula I to be used as starting materials can be prepared by customary methods of amino acid and peptide synthesis, as described, for example, in US Pat. B. are described in said standard works and patent applications, e.g. also according to the solid phase method according to Merrifield (B.F. Gysin and R.B. Merrifield, J. Am. Chem. Soc. 24, 3102ff. (1972)).

Depending on the protective group used, the compounds of formula I can be liberated from their functional derivatives, for example with strong acids, expediently with TFA or perchloric acid, but also with other strong inorganic acids such as hydrochloric acid or sulfuric acid, strong organic carboxylic acids such as trichloroacetic acid or sulfonic acids such as benzene or p-toluenesulfonic acid. The presence of an additional inert solvent is possible, but not always required. Suitable inert solvents are preferably organic, for example carboxylic acids such as acetic acid, ethers such as tetrahydrofuran or dioxane, amides such as DMF, halogenated hydrocarbons such as dichloromethane, and also alcohols such as methanol, ethanol or isopropanol and water. Mixtures of the aforementioned also come

Solvent in question. TFA is preferably used in excess without the addition of another solvent, perchloric acid in the form of a mixture of acetic acid and 70% perchloric acid in a ratio of 9: 1. The reaction temperatures for the cleavage are advantageously between about 0 and about 50 °, preferably one works between 15 and 30 ° (room temperature).

The groups BOC, OBut and Mtr can e.g. B. preferably with TFA in dichloromethane or with about 3 to 5 n H Cl in dioxane at 15-30 °, the Fmoc group with an about 5 to 50% solution of dimethylamine, diethylamine or piperidine in DMF at 15-30 °.

Protective groups which can be removed hydrogenolytically (for example CBZ or benzyl) can be removed, for example, by treatment with hydrogen in the presence of a catalyst (for example a noble metal catalyst such as palladium, advantageously on a support such as carbon). Suitable solvents are those mentioned above, in particular, for example, alcohols such as methanol or ethanol or amides such as DMF. The hydrogenolysis is generally carried out at temperatures between about 0 and 100 ° and pressures between about 1 and 200 bar, preferably at 20-30 ° and 1-10 bar. Hydrogenolysis of the CBZ group is successful, for example, on 5 to 10% Pd-C in methanol or with ammonium formate (instead of H ₂ ) on Pd-C in methanol / DMF at 20-30 °.

Compounds of the formula I can also be reacted by reacting a compound of the formula II with an amino compound of the formula III under condensing conditions known per se for peptide synthesis, as described, for example, in Houben-Weyl, Ie, vol. 1-5 / 11, p 1-806 (1974). The reaction is preferably carried out in the presence of a dehydrating agent, for example a carbodiimide such as DCCI or EDCI, and also propanephosphonic anhydride (cf. Angew. Chem. 92, 129 (1980)), diphenylphosphoryl azide or 2-ethoxy-N-ethoxycarbonyl- 1,2-dihydroquinoline, in an inert solvent, for example a halogenated hydrocarbon such as dichloromethane, an ether such as tetrahydrofuran or dioxane, an amide such as DMF or dimethylacetamide, a fSIrtril such as acetonitrile, or in mixtures of these solvents, at temperatures between about -10 and 40, preferably between 0 and 30 °.

Instead of II, suitable reactive derivatives of these substances can also be used in the reaction, e.g. those in which reactive groups are temporarily blocked by protective groups. The amino acid derivatives II can e.g. in the form of their activated esters, which are conveniently formed in situ, e.g. by adding HOBt or N-hydroxysuccinimide.

The starting materials of formula II are usually new. You can use known methods, e.g. the above-mentioned methods of peptide synthesis and deprotection.

As a rule, protected peptide esters of the formula R'-M'-OR "are first synthesized, where M 'corresponds to the radical M which is reduced by one H atom at the N-terminal end, for example BOC-M'-O Me or Fmoc-M'-O Me. These are saponified to acids of the formula R'-M'-OH, for example BOC-M'-OH or Fmoc-M'-OH and then with a compound of the formula III, which may also be by appropriate protective groups are provided at positions which should not be accessible to the reaction.

In the case of compounds of the formula III, peptide esters of the formula R'-QZ '-R "are also synthesized, such as, for example, BOC-QZ'-O Me or Fmoc-Q-Z'-O Me, where Z'-NH- or - 0 means and then cleaves off the protective group R 'in a known manner, for example Fmoc by treatment with a piperidine / DMF solution, before the condensation for the preparation of compounds of the formula I is carried out. The newer methods of peptide synthesis according to modified Merrifield techniques and using peptide synthesizers, as described, for example, in Peptides, Proc. 8th am Pept. Symp., Eds. V. Hruby and DH Rieh, Pierce Comp. III, p. 73-77 (1983) by A. Jonczyk and J. Meinenhofer (Fmoc strategy) or which are described in Angew. Chem. 104. 375-391 (1992) find the techniques used. Such methods are known per se and their description is therefore unnecessary at this point.

A base of the formula i can be converted into the associated acid addition salt using an acid. In particular, acids that provide physiologically acceptable salts are suitable for this implementation. So inorganic acids can be used, e.g. Sulfuric acid, nitric acid, hydrohalic acids such as chlorohydrogen acid or hydrobromic acid, phosphoric acids such as orthophosphoric acid, sulfamic acid, furthermore organic acids, in particular aiphatic, alicyclic, araliphatic, aromatic or heterocyclic mono- or polybasic carboxylic, sulfonic or sulfuric acids, e.g. Formic acid, acetic acid, propionic acid, pivalic acid, diethylacetic acid, malonic acid, succinic acid, pimelic acid, fumaric acid, malic acid, lactic acid, tartaric acid, malic acid, benzoic acid, salicylic acid, 2- or 3-phenylpropionic acid, citric acid, giuconic acid, asotorbic acid, isotonic acid, ascorbic acid, ascorbic acid - or ethanesulfonic acid, ethanedisulfonic acid, 2-hydroxyethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalene mono- and disulfonic acids, laurylsulfonic acid. Salts with physiologically unacceptable acids, e.g. Picrates can be used for the isolation and / or purification of the compounds of the formula I.

On the other hand, an acid of the formula I can be reacted with a

Base are converted into one of their physiologically acceptable metal or ammonium salts. In particular, the sodium, potassium, magnesium, calcium and ammonium salts come in as salts Consider, further substituted ammonium salts, such as the dimethyl, diethyl or diisopropylammonium salts, monoethanol, diethanol or triethanolammonium salts, cyclohexyl, dicyclohexylammonium salts, dibenzylethylenediammonium salts, furthermore, for example, salts with N-methyl-arginine or glaminamine or l.

The invention further relates to synthetic peptide layers consisting of one or more peptides of the formula I according to claim 1, which are covalently bonded to a gold surface via a -Sulfur or -S-S bridge, characterized in that the

C-terminal groups are linked amide-like with a further peptide sequence with donor properties, so that bonds to corresponding acceptor molecules can be produced.

The peptide derivatives of the formula I, which can be covalently bonded to gold surfaces at the N-terminal via sulfur-containing anchors and substituted at the C-terminal with other peptides or lipids, organize themselves into single layers on the gold surface, in particular if self-organization is supported by long hydrophobic residues of the sulfur-containing anchors or the conformation of the peptides favors layer formation. It is possible to measure the organization and density of these layers by physical methods, such as cyclic voltammetry and impedance spectrometry, as long as the capacitance and / or resistance changes due to long hydrophobic chains.

These single layers present peptide structures away from the gold layer that can act as ligands for acceptor molecules. An interaction between bound ligands and the acceptor molecules can be measured, for example, by surface plasmon resonance. Such peptide layers can accordingly be used to investigate a wide variety of acceptor molecules. Acceptor molecules include, for example, receptors, enzymes, pump or channel proteins. Pump or channel proteins and membrane-spanning receptors only bind if they can be incorporated into a lipid layer at the same time. These peptides can therefore be used either directly or coupled to a lipid as ligands for acceptor molecules.

The model can therefore e.g. can be used for a screening test of inhibitors, of ion pumps, for the investigation of ion channels or for the construction of sensors for substrates and inhibitors of pump proteins. For example, herbicides can be detected that inhibit the photochemical reaction center.

By incubation with liposomes, the single layers can be provided with a second layer, hydrophobic and hydrophilic layers being arranged in such a way that the middle hydrophobic double layer on the side of the gold surface through the hydrophilic peptide layer and away from the gold surface into the aqueous medium through a hydrophilic Delimited layer of the former liposome. The length of the peptide chain, in particular in its 3-dimensional fold, thus determines the thickness of the gold-containing hydrophilic layer.

These double layers are imitations of cell membranes and can e.g. Stably incorporate transmembrane proteins (e.g. receptors). It is possible to insert channel-forming or ion-transporting proteins and their function e.g. to be examined by impedance spectrometry.

The invention also relates to synthetic cell membranes, characterized in that they consist of a gold support which is covalently linked to a peptide of the formula I according to claim 1 via a sulfur bridge, the C-terminal side of the peptide in turn being linked to lipid residues, which in turn form a membrane-analogous lipid bilayer with the liposomes present. To build up the synthetic membranes, the monomolecular peptide layers, which are covalently bound to a gold surface via peptidic spacers, are provided with a second lipid layer by rolling out liposomes or by means of the Langmuir-Blodgett technique, so that defined lipid bilayers are formed, which in this respect form a Represent a model of a biological membrane as it adjoins a water phase on both sides. The peptide spacer is used to form a hydrophilic layer between the hydrophobic lipid layer and the gold surface.

The C-terminal groups of the peptides can couple in an amide-like manner with lipids which have an NH ₂ group, for example with dimyristoylphosphatidylamine, dipalmitoylphosphatidylamine, dioleylphosphatidylamine, natural kephalins, natural phosphate idylethanolamine or with long-chain primary amylamine, for example.

The coupling can be in-situ or ex-situ, i.e. done in solution. In the latter case, the entire molecule binds to the gold.

in all cases, a construct consisting of lipid with long hydrophobic chains is formed, which is bound to the gold via the peptide as a spacer. Alternatively, Pt, Pd, Ag or Cu can be used. These connections tend to self-organize.

They are able to insert functional membrane proteins and thus allow, for example, their electrical, structural and binding properties to be investigated.

Liposomes consisting of phosphatidylcholine and phosphatidic acid are particularly suitable for the formation of the double layers.

Defined bilayers are formed by the fusion of liposomes above the transition temperature of the lipid. The formation of these bilayers was measured in real time using the Surface Plasmon Resonance Spectroscopy (SPRS). Liposomes with incorporated ATPase from chloroplasts

(CF ₀ F,) and from E. coli (EF ₀ F,) form bilayers with inserted protein. This was proven with SPRS: The layer thickness for the "empty" bilayer is 4.0 nm and for the bilayer with incorporated ATPase 6.0 or 8.5 nm depending on the concentration of the ATPases. Compared to this, the calculated layer thickness of an empty bilayer is 5 nm and the length of the ATPase is 8.5 nm. The packing density of the layers was determined using X-ray reflectometry. It is 100% for the peptide layer and 60% for the monolayer. The composition of the monolayer covalently bound to the gold was verified by FTIR spectroscopy. The capacitance was determined by cyclic voltammetry and impedance spectrometry (2 and 1 μF / cm2). The activity of the enzyme in the lipid bilayer was demonstrated by coupling the proton translocation to the discharge of the protons at the gold electrode using fast pulse techniques such as double potential pulse chronoamperometry and square wave voltammetry. With the latter technique, the activity of the enzyme can be determined quantitatively, taking into account the effect of the electric field. The activity can also be measured depending on the activation potential. The bilayer with the incorporated enzyme is retained in all measurements even after rinsing with buffer. The measurements can be carried out several times on the same sample. The activity can be suppressed by known specific inhibitors.

Immobilizing the enzymes on the gold surface opens up possibilities for determining the structure and conformation of the membrane proteins using atomic force microscopy, among other things. surface physical methods.

In addition to the pump protein, ion channel-forming proteins, ionophores and enzymes in general can also be inserted.

It is also possible to incorporate different types of receptors into the membrane. It is then also possible, for example, to use layer thickness measurements, for example surface plasmon resonance spectroscopy, to investigate dynamic processes at the receptor in addition to static effects. The invention accordingly furthermore relates to synthetic cell membranes, characterized in that the double layer on the side of the gold surface is delimited by the hydrophilic peptide layer and in the direction of the other side which projects into the aqueous medium by the hydrophilic head groups of the former liposomes , where proteins are stably incorporated into the membranes.

The invention also relates to synthetic cell membranes which contain light-driven proteins such as e.g. Contain bacteriorhodopsin and can therefore be used as solar cells. Such a solar cell can e.g. be constructed in such a way that a peptide, lipid mono- or lipid bilayer and a layer of the light-sensitive pump protein is layered in the order given on a metal electrode, preferably a noble metal electrode consisting of Au, Pt, Pd or Cu. Such a layer structure is suitable for the inherent potential of the

Pump protein, which it takes on exposure to pass on to the electrode and form a barrier for the protons, which are then transported through the protein so that they are prevented from back diffusion. The protons are discharged at the metal electrode. The potential that is created by the exposure to the

Electrode. This potential can be modulated by a suitable interruption of the exposure, so that a potential is set at the electrode, in which the evolution of hydrogen takes place. This leads to spontaneous hydrogen evolution, ie without applying any voltage. Hydrogen can thus be generated by exposure of the modified cell membrane.

Alternatively, electricity can be generated directly if the hydrogen formed on the cathode is reduced back to protons at the anode.

The invention further relates to a process for the production of the synthetic cell membranes, characterized in that a gold-coated substrate is introduced into a solution of a peptide or a peptide-analogous compound of the formula I, which is obtained, for example, by Treatment with diisopropylcarbodiimide is activated, coupled with the lipid component and converted into a defined lipid bilayer by adding liposomes. The liposomes can contain proteins of various types, the ones already mentioned being particularly suitable.

To produce the membranes, the peptides of the formula I which have disulfide or SH groups or free carboxyl groups are, for example, drawn onto a gold-coated gum support, so that the peptide is covalently bonded to the via an Au-SC bond Gold bearer connects. These peptide constructs are activated in situ via an activation of the COOH group with e.g. Diisopropylcarbodiimide, for example coupled with dimyristoylphosphatidylethanolamine, so that a lipid monolayer is formed on the gold base, which is bound to the gold via the peptide spacer molecule. The monolayer forms during coupling through self-assembly (self-assembly) because the long myristoyl residues tend to aggregate parallel to the chain. In the presence of liposomes without and with incorporated transmembrane proteins, such monolayers form defined bilayers which are stably attached to the support.

However, it is particularly advantageous to synthesize a molecule which consists from the start of a hydrophilic spacer and a lipid or long-chain alkyl compound which covalently binds to gold via a terminal SH or -S-S group and is self-organized from arranges itself (seif assembly).

The coupling therefore does not necessarily have to take place in situ.

The invention furthermore relates to the use of the synthetic cell membranes for the investigation

(a) interactions of ligand and acceptor molecules in membrane models; (b) receptor binding processes and for performing receptor binding assays;

(c) of processes which take place in ion channels with proteins forming ion channels and

(d) the efficacy of drugs, e.g. with regard to their membrane permeability and / or their toxic effect.

Furthermore, the use of synthetic cell membranes for

Structure of sensors, in particular biosensors and for the construction of bioelectronic components, object of the invention.

All temperatures above and below are given in ° C. In the examples below, "customary work-up" means: if necessary, water is added, neutralized, extracted with ether or dichloromethane, separated, the organic phase is dried over sodium sulfate, filtered, evaporated and purified by chromatography on silica gel and / or HPLC. RT = retention time (minutes) with HPLC on Lisorb »select B (250 x 4 column, eluent: 0.3% TFA in water; isopropanol gradient from 0-80 vol% in 50 min. At 1 ml / min. Flow and detection at 215 nm. M * + 1 = molecular peak in the mass spectrum, obtained by the "Fast Atom Bombardment" method (FAB), generally stands for M + + H, that is to say the mass of the respective compound increased by 1 unit of mass .

The substances were generally synthesized according to the prior art on Wang resin in an Fmoc strategy with acid-labile side-protecting groups. The N-terminal derivatization was achieved by reaction with 3-tritylmercaptopropionic acid or lipoic acid. After cleavage with trifluoroacetic acid / dichloromethane / anisole and ether precipitation, the crude product in the case of the trityl derivatives was gel-filtered on Sephadex G10® by dissolving in triphenylmethanol / trifluoroacetic acid and purified by HPLC. No triphenylmethanol was used in the case of lipoic acid. The following examples are intended to describe the invention in more detail, but without restricting it.

Even without further explanations, it is assumed that a person skilled in the art can use the above description in the broadest scope. The preferred embodiments are therefore only to be understood as a descriptive disclosure, in no way as a limitation in any way.

The complete disclosure of all the applications, patents and publications mentioned above and below, and the corresponding application P 4444 893.7, filed on December 16, 1994, are incorporated by reference into this application.

Examples

example 1

0.6 g of Fmoc-Lys (BOC) -OH are dissolved in 100 ml of dichloromethane, 1.2 equivalents of Wang resin (p-benzyloxybenzyl alcohol resin), 1.2 equivalents of HOBt and 1.2 equivalents of DIC are added and Stirred for 12 hours at room temperature. After removal of the solvent, Fmoc-Lys (BOC) -Wang resin is obtained. In the peptide synthesizer, Fmoc-Pro-OH is condensed with H-Lys (BOC) -Wang resin [release from Fmoc-Pro-Wang resin with piperidine / DMF (20%)) by using a triple excess of the protected proline. The coupling is carried out in DCCI / HOBt at room temperature. Fmoc-Pro-Lys (BOC) -Wang resin is obtained. Subsequent treatment with piperidine / DMF (20%) provides H-Pro-Lys (BOC) -Wang resin. Example 2

Analogously to Example 1, Fmoc-Ala-Wang resin is obtained by repeated condensation with Fmoc-Ala-OH in a peptide synthesizer (continuous flow principle) after performing the following steps:

Release of H-Ala-Wang resin with piperidine / DMF (20%)

Reaction with Fmoc-Ala-OH in DCCI / HOBt at room temperature

Washing and treatment with piperidine / DMF (20%)

Coupling of the resulting H-Ala-Ala-Wang resin with Fmoc-Ala-OH

Washing and treating the resulting Fmoc-Ala-Ala-Ala-Wang resin with piperidine / DMF and then repeating the condensation step twice with Fmoc-Ala-OH

Fmoc-Ala-Ala-Ala-Ala-Ala-OH.

H-Ala-Ala-Ala-Ala-Ala-Wang resin is released by treatment with piperidine / DMF (20%).

You get analog

Fmoc-Gly-Gly-Gly-OH.

Example 3

Analogously to Example 2, starting from Fmoc-Ala-Wang resin, after carrying out the corresponding reaction steps and reintroducing the side chain protective groups (butylation of Ser), coupling with Fmoc-Ser (But) -OH, Fmoc-Ala- OH, Fmoc-Ala-OH, Fmoc-Ser (But) - OH, Fmoc-Ser (But) -OH and Fmoc-Ala-OH in that order the Fmoc-Ala-Ser (But) -Ser (But) - Ala-Ala-Ser (But) -Ala-OH. Subsequent treatment with piperidine / DMF (20%) provides:

H-Ala-Ser (But) -Ser (But) -Ala-Ala-Ser (But) -Ala-OH.

Example 4

Analogously to Example 2, H-Pro-Lys (BOC) -Wang resin is obtained after carrying out the corresponding reaction steps and reintroducing the protective groups from the site by coupling with Fmoc-Ser (But) -OH, Fmoc-Asp (OBut) -OH, Fmoc-Gly-OH, Fmoc-Arg (Mtr) -OH and Fmoc-Gly-Gly-Gly-OH in that order the Fmoc-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut ) -Ser (But) -Pro-Lys (BOC) -Wang resin.

Subsequent treatment with piperidine / DMF (20%) provides:

H-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin.

Example 5

0.4 g H-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) - Wang resin are included in the peptide synthesizer (continuous flow principle) Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -COOH (RT 35.9 min., M + + 1 = 531) condens¬ by using a triple excess of the acid. The coupling is carried out in DCCI HOBt at room temperature. Trt-S-tCH ^ rCO-NH- ^ H ^ w.-CO-Gly-Gly-Gly-ArgfMt -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin is obtained . Subsequent treatment with TFA CH ₂ CI ₂ in the presence of water gives Trt-S-fCH ^ .- CO-NH- (CH ₂ ) ₁₀ , -CO-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro- Lys (BOC) -OH.

Analogously one obtains by condensation of Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ), o-COOH

with H-Ala-Ala-Ala-Ala-Ala-Wang resin and subsequent separation from the resin: Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ιo-CO-Ala-Ala-Ala-Ala-Ala-OH;

with H-Ala-Ser (But) -Ser (But) -Ala-Ala-Ser (But) -Ala- Wang resin and subsequent cleavage from the resin: Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH.

Example 6

Analogously to Example 5, condensation of H-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin in a peptide synthesizer (continuous flow Principle) with HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ - COOH the HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg (Mtr) -Gly- Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin. Subsequent treatment with TFA / CH ₂ CI ₂ in the presence of water yields HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser- Pro-Lys-OH.

Analogously, condensation of HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -COOH is obtained

with H-Ala-Ala-Ala-Ala-Ala-Wang resin and subsequent cleavage from the resin: HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ala-Ala-Ala -Ala-OH;

with H-Ala-Ser (But) -Ser (But) -Ala-Ala-Ser (But) -Ala-Wang resin and subsequent cleavage from the resin:

HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH.

Example 7

Analogously to Example 5, condensation of H-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin in a peptide synthesizer (continuous flow Principle) with Trt-S- (CH ₂ ) ₂ -COOH (RT 34.5 min., M * + 1 = 347) the Trt-S- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg (Mtr) - Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin. Subsequent treatment with TFA / CH ₂ CI ₂ in the presence of water provides Trt-S- (CH ₂ ) ₂ - CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH.

Analogously, the Trt-S- (CH ₂ ) ₂ -CO-Ala-Ala is obtained by condensation of Trt-S-fCH ^ rCOOH with H-Ala-Ala-Ala-Ala-Ala-Wang resin and subsequent cleavage from the resin -Ala-Ala-Ala-OH; with H-Ala-Ser-Ser-Ala- Ala-Ser-Ala-Wang resin and subsequent cleavage from the resin the Trt-S- (CH ₂ ) ₂ -CO-Ala-Ser-Ser-Ala-Ala-Ser- Ala-OH.

Example 8

Analogously to Example 5, condensation of H-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin in a peptide synthesizer (continuous flow Principle) with 1, 2-dithiolan-3-pentanoic acid (lipoic acid) the Liponyl-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) - Pro-Lys (BOC) - Wang- Resin. Subsequent treatment with TFA / CH ₂ CI ₂ in the presence of water provides Liponyl-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH.

Analogously, the liponyl-Ala-Ala-Ala-Ala-Ala-OH is obtained by condensation of lipoic acid with H-Ala-Ala-Ala-Ala-Ala-Wang resin and subsequent cleavage from the resin; RT 21.7 min., M + + 1 = 562; with H-Ala-Ser (But) - Ser (But) -Ala-Aia-Ser (But) -Ala-Wang resin and subsequent cleavage from the resin the liponyl-Ala-Ser-Ser-Ala-Ala-Ser-Ala -OH.

Example 9

0.3 g Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg (Mtr) -Gly-

Asp (OBut) -Ser (But) -Pro-Lys (BOC) -OH are taken up in 30 ml of 2N HCl based on dioxane and stirred for 2 hours at room temperature. The reaction mixture is then evaporated to dryness and the Residue treated with TFA C ^ CI ^ anisole, precipitated by adding diethyl ether, dissolved in triphenylmethanol / TFA / water and gel filtered on Sephadex G10®. Subsequent purification by HPLC provides Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH.

Analogously, one gets starting by removing the protecting groups

of Trt-S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ser (But) -Ser (But) -Ala-Ala- Ser (But) -Ala-OH the: Trt -S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH;

of Trt-S- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro- Lys (BOC) -OH the:

Trt-S- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH;

of Trt-S- (CH ₂ ) ₂ -CO-Ala-Ser (But) -Ser (But) -Ala-Ala-Ser (But) -Ala-OH das: Trt-S- (CH ₂ ) ₂ -CO -Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH; RT 33.0 min., M + + 1 = 895.

Example 10

Analogously to Example 5, condensation of H-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -Wang resin in a peptide synthesizer (continuous flow Principle) with HS-fCH ^ -COOH the HS- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-

Lys (BOC) -Wang resin. Subsequent treatment with TFA / CH ₂ CI ₂ in the presence of water provides HS- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH.

Analogously one obtains by condensation of HS- (CH ₂ ) ₂ -COOH with

H-Ala-Ala-Ala-Ala-Ala-Wang resin and subsequent cleavage from the resin the HS- (CH ₂ ) ₂ -CO-Ala-Ala-Ala-Ala-Ala-OH; with H-Ala-Ser (But) - Ser (But) -Ala-Ala-Ser (But) -Ala-Wang resin and subsequent cleavage from the resin the HS- (CH ₂ ) ₂ -CO-Ala-Ser-Ser -Ala-Ala-Ser-Ala-OH. Example 11

0.5 g HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ιo-CO-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) - Ser (But) -Pro-Lys (BOC ) -OH are taken up in 30 ml of 2N HCl based on dioxane and stirred for 2 hours at room temperature. The reaction mixture is then evaporated to dryness and the residue is treated with TFA / C ^ Cl ^ anisole, precipitated by adding diethyl ether, dissolved in TFA / water and gel filtered on Sephadex G10®. Subsequent purification by HPLC provides HS-fCHs rCO-NH-fCH ^ o-CO-Gly-Gly-G! Y-Arg-Gly-Asp-Ser-Pro-Lys-OH.

Analogously, one gets starting by removing the protecting groups

of HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ser (But) -Ser (But) -Ala-Ala- Ser (But) -Ala-OH the:

HS- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH;

of HS- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro- Lys (BOC) -OH the: HS- (CH ₂ ) ₂ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH;

of HS- (CH ₂ ) ₂ -CO-Ala-Ser (But) -Ser (But) -Ala-Ala-Ser (But) -Ala-OH das: HS- (CH ₂ ) ₂ -CO-Ala-Ser -Ser-Ala-Ala-Ser-Ala-OH; Rt 2.9 min, M + + 1 = 652;

Liponyl-Gly-Gly-Gly-Arg (Mtr) -Gly-Asp (OBut) -Ser (But) -Pro-Lys (BOC) -

Oh that:

Liponyl-Gly-Gly-Gly-Argy-Gly-Asp-Ser-Pro-Lys-OH;

from Liponyl-Ala-Ser (But) -Ser (But) -Ala-Ala-Ser (But) -Ala-OH that: Liponyl-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH.

The following examples relate to peptide monolayers and lipid bilayers. Example A

Gold electrodes made of electrothermally evaporated gold of 0.94 c 2 area are cleaned overnight in chromosulfuric acid, then rinsed with water and then with methanol and dried. The electrodes thus cleaned are placed in a solution of a mercapto or trityl mercaptopeptide of the formula I in trifluoroacetic acid (1 mg / ml) and incubated therein for 96 hours. Then they are rinsed in succession with dimethylformamide (DMF) and dichloromethane and dried.

The following peptide layers bound to gold are obtained:

(a) Au _x - [S- (CH ₂ ) ₂ -CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OH] _y ;

(b) AUx-fS-fCHzk-CO-Ala-Ser-Ser-Ala-Ala-Ser-Ala-OHj _y ;

(c) Au _x - [S- (CH ₂ ) ₂ -CO-Ala-Ala-Ala-Ala-Ala-OH] _y ;

(d) Au _x - [S- (CH ₂ ) ₂ -CO-Ala-Ala-Ala-Ala-Ala-OH] _y ;

(e) Au _x - [5- (1,2-dithiocyclopentan-3-yl) pentanoyl-Ala-Ala-Ala-Ala-Ala-OH] _y ;

(f) Au _x - [S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH] _y ,

(g) Au _x - [S- (CH ₂ ) ₂ -CO-NH- (CH ₂ ) ₁₀ -CO-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-Lys-OH] _y .

The indices "x" and "y" should indicate that they are polymolecular units. Example B

Coupling the peptide layers with dimyristoylphosphatidylethanolamine (DMPE) to produce the lipid monolayer (in situ coupling)

The gold electrodes (a) to (g) coated with the peptides as described above are dissolved in a solution of DMPE (1 mg / ml), HOBT (0.2 mg / ml) and LiCl (5 mg / ml) DMF and dichloromethane (1: 1) activated with diisopropylcarbodiimide (40 μl / ml). After the addition of N-ethyl-diisopropylamine, they are then incubated for 96 hours. This coupling procedure is carried out once more with fresh solutions, the monolayer forming. Finally, the electrodes are rinsed with DMF and dichloromethane and dried.

Example C

Production of the lipid bilayers

Coated with lipid monolayer electrodes are at 30 ° C in a suspension of liposomes with and without the incorporated ATPase of E. coli: EFQF, (lipid ^* 0.24 mg / ml, EF _O F _T 18 nmol / l) incubated for 30 min . Phosphatidylcholine is used as lipid.

Alternatively, they are provided with the second lipid layer, for example from phosphatidylcholine and phosphatidic acids, using the Langmuir-Schäfer or the Langmuir-Blodgett technique (ref. Cit.). The "empty" bilayers also insert the enzyme in contact with liposomes with incorporated ATPase. Try with the Bilayers

The formation of the bilayer is followed by surface plasmon resonance spectroscopy. The layer thickness of the bilayer with and without the enzyme was determined to be 8.5 and 4 nm. The former corresponds to the longitudinal expansion of the ATPase, while the "empty" bilayer should have a layer thickness of 4-5 nm. The incorporation of the enzyme into the bilayer has thus been demonstrated.

The tightness of the layers is checked by cyclic voltammetry and impedance spectrometry.

The ATPase EFoF _t is an enzyme that catalyzes the hydrolysis of ATP and the coupled translocation of protons across the membrane. The function of the enzyme can therefore be demonstrated by changing the proton concentration at the gold electrode. The proton concentration is measured by square wave voltammetry of the proton discharge to hydrogen. It can be seen that the signal of the proton discharge increases with the concentration of ATP in the solution.

Example P

Analogous to Example C, lipid bilayers are produced in which ATPase CFoF, from chloroplasts, is incorporated.

Example E

Analogous to Example C, lipid bilayers are produced in which bacteriorhodopsin from purple bacteria is incorporated.

Claims

claims

1. Peptides or peptide-analogous compounds of the formula I.

R-A-B-C-D-E-OH I,

wherein

A an amino acid residue selected from a group consisting of Ala, Gly or Leu,

B an amino acid or dipeptide residue selected from a group consisting of Ala, Ser, Gly-Gly and Ser-Ser,

C an amino acid, di or tripeptide residue selected from a group consisting of Ala, Ala-Ala, Leu-Leu, Ala-Ala-Ala, Arg-Gly-Asp and Leu-Leu-Leu,

D an amino acid residue selected from a group consisting of Ala and Ser,

E an amino acid or dipeptide residue selected from a group consisting of Ala, Leu and Pro-Lys,

R H, HS-alkyl-CO-, HS-alkyl-CO-NH-alkyl'-CO-,

Trt-S-alkyl-CO-, Trt-S-alkyl-CO-NH-alkyl'-CO- or 1,2-dithiocyclopentane-3- (CH2) ₄ -CO-, where R can only be H if at least one of the radicals A, B, C, D or E is not Ala,

alkyl and alkyl 'each independently of one another an alkylene radical having 1 to 11 carbon atoms and

Trt triphenylmethyl

mean, and their salts.

2. A process for the preparation of a compound of formula I according to claim 1, characterized in that it is liberated from one of its functional derivatives by treatment with a solvolysing or hydrogenolysing agent or that one

Compound of formula II

M-OH II,

wherein

M R, but not hydrogen, R-A, R-A-B, R-A-Gly,

R-A-B-C, R-A-B-Leu, R-A-B-Arg, R-A-B-Arg-Gly or R-A-B-C-D

means

with an amino compound of formula III

H-Q-OH III

wherein

Q E, Lys, D-E, C-D-E, Leu-D-E, Asp-D-E, Gly-Asp-D-E, B-C-D-E, Gly-C-D-E, A-B-C-D-E or NH-alkyl'-CO-

A-B-C-D-E

means

implements.

3. Synthetic peptide layer consisting of one or more peptides of the formula I according to claim 1, which is covalently bonded via sulfur bridges to a gold surface, characterized in that the C-terminal groups are linked amide-like with a further peptide sequence with donor properties, so that Bonds to corresponding acceptor molecules can be made.

4. Synthetic cell membranes, characterized in that they consist of a gold carrier which is covalently linked to a peptide

Formula I according to claim 1 is connected via a sulfur bridge, the C-terminal side of the peptide in turn being linked to lipid residues, which in turn form a membrane-analogous lipid bilayer with the liposomes present.

5. Synthetic cell membranes according to claim 4, characterized gekenn¬ characterized in that the lipid bilayer on the side of the gold surface through the hydrophilic peptide layer and in the direction of the other side, which projects into the aqueous medium, through the hydrophilic layer the former liposomes is limited and into the

Membranes proteins are incorporated stably.

6. Synthetic cell membranes according to one or more of claims 3, 4 and 5, characterized in that they contain inserted light-driven proteins and can serve as a solar cell.

7. A method for producing the synthetic cell membranes according to claims 5 and 6, characterized in that

(a) a gold-plated substrate in a solution of a

Introduces peptides or a peptide-analogous compound of the formula I according to claim 1 which is activated, coupled to the lipid component and converted into a defined lipid bilayer by adding liposomes with or without incorporated protein, or in that (b) Build up the membranes using the Langmuir-Blodgett technique.

8. A process for the production of synthetic cell membranes according to claim 7, characterized in that the liposomes used contain transmembrane proteins.

9. Use of the synthetic cell membranes according to claims 3, 4, 5 and 6 for the investigation of kinetic effects caused by the interaction between ligand and acceptor molecules or by test substances with inserted membrane proteins in the

Membrane model can be induced / or by processes that take place in the ion channels of membranes.

10. Use of the synthetic cell membranes according to claims 4, 5 and 6 for the time-dependent execution of a

Receptor binding assays and for the investigation of processes at receptors.

11. Use of the synthetic cell membranes according to claims 4, 5 and / or 6 for the construction of sensors, in particular

Biosensors.

12. Use of the synthetic cell membranes according to claims 4, 5 and 6 for examining the effectiveness of drugs and crop protection agents.