Opioid metallopeptide compositions and methods

Abstract

Metallopeptides and metallopeptide combinatorial libraries specific for opioid receptors are provided, for use in biological, pharmaceutical and related applications. The metallopeptides and combinatorial libraries are made of peptides, peptidomimetics and peptide-like constructs, in which the peptide, peptidomimetic or construct is conformationally fixed in a biologically active configuration specific for one or more opioid receptors on complexation of a metal ion-binding portion thereof with a metal ion.

1 . A metallopeptide comprising a peptide sequence of the formula  
         R 5 —R 11 —R 13 —R 3 —R 10   VI  
       wherein 
 R 3  is L- or D-Cys, L- or D-homoCys, L- or D-Pen or a derivative or homolog of any of the foregoing, with both an —N and —SH available for complexation to a metal ion;  
 R 5  is an L- or D-amino acid with a phenol moiety side chain, excluding des-carboxy derivatives;  
 R 10  is a free carboxylate, primary amide or aryl or aralkyl chain substituted amide of R 3 , or an L- or D-amino acid with a neutral aromatic side chain or side chain with a ring substituted halogen, nitro or alkyl group;  
 R 11  is L- or D-Cys, L- or D-homoCys, L- or D-Pen or a derivative or homolog of the foregoing, with an —SH available for complexation to a metal ion; and  
 R 13  is an L- or D-amino acid with a neutral aliphatic or aromatic side chain or side chain with a ring substituted halogen, nitro or alkyl group, with an —N available for complexation to a metal ion.  
 
     
     
         2 . The metallopeptide of  claim 1  with the structure  
       
         
           
           
               
               
           
         
       
       wherein 
 M is the metal ion; and  
 R 13 ′ is a neutral aliphatic or aromatic side chain or side chain with a ring-substituted halogen, nitro or alkyl group.  
 
     
     
         4 . The metallopeptide of  claim 1  wherein R 5  is an L- or D-configuration of Tyr, homoTyr, or p-hydroxy-phenylglycine, N-alkylated, N-arylated, or N-aralkylated derivatives of Tyr, homoTyr, or p-hydroxy-phenylglycine, Ser(O-(p-hydroxy)benzyl), Thr(O-(p-hydroxy)benzyl), Cys(S-(p-hydroxy)benzyl), Lys(N-epsilon(p-hydroxy)phenyl), Lys(N-epsilon(p-hydroxy)benzyl), or a homolog or des-amino acid derivative of the foregoing.  
     
     
         4 . The metallopeptide of  claim 1  wherein R 10  is an L- or D-configuration of Phe, homoPhe, Phg, NaI, Trp, Dip, Bip, Ser(O-benzyl), Thr(O-benzyl), Cys(S-benzyl), homologs wherein the aromatic ring is substituted with a halogen, nitro or alkyl group or a des-carboxyl derivative of the foregoing.  
     
     
         5 . The metallopeptide of  claim 1  wherein R 13  is Gly or an L- or D-configuration of Ala, Nle, Val, Leu Phe, homoPhe, Phg, NaI, Trp, Dip, Bip, Ser(O-benzyl), Thr(O-benzyl), Cys(S-benzyl) or a homolog thereof.  
     
     
         6 . The metallopeptide of  claim 1  wherein the metal ion is an ionic form of rhenium or technetium.  
     
     
         7 . The metallopeptide of  claim 1  wherein the peptide sequence comprises Tyr-Cys-Gly-Cys-NH 2  (SEQ ID NO:19).  
     
     
         8 . A manufactured peptide and pharmaceutically acceptable salts thereof comprising a metal ion-binding domain comprising three contiguous amino acids and a determined biological-function domain comprising a phenol moiety and a phenyl moiety specific for one or more opioid receptors, wherein at least a portion of said biological-function domain is co-extensive with at least a portion of the metal ion-binding domain, and wherein said biological-function domain is conformationally constrained upon complexing the metal ion-binding domain with a metal ion.  
     
     
         9 . The peptide of  claim 8  wherein the metal ion-binding domain is complexed with a metal ion.  
     
     
         10 . The peptide of  claim 8  wherein the composition is substantially more specific for one or more opioid receptors when complexed with a metal ion than is the composition when not complexed with a metal ion.  
     
     
         11 . A combinatorial library targeted to opioid receptors of different sequence peptide members synthesized on solid phase, where each constituent library member comprises: 
 (a) a peptide sequence of three or more amino acid residues bound to solid phase characterized by (i) a sequence of two or more amino acid residues forming a metal ion-binding domain and including at least one amino acid residue containing at least one S wherein the said S is protected by an orthogonal S-protecting group, (ii) a sequence of one or more amino acid residues at the N- or C-terminus of the metal ion-binding domain, or at both the N- and C-terminus of the metal ion-binding domain, and (iii) a cleavable bond attaching the peptide sequence to solid phase, wherein each peptide sequence comprises a phenol moiety and a phenyl moiety; and    (b) a unique selection or sequence of amino acid residues in the peptide sequence of at least one of the constituent members of the library;    wherein the orthogonal S-protecting group may be removed without cleaving the peptide sequence from the solid phase.    
     
     
         12 . The combinatorial library of  claim 11  wherein the metal ion-binding domain further comprises at least one N available for binding to a metal ion upon removal of the orthogonal S-protecting group, and preferably comprises three residues forming an N 3 S 1  ligand.  
     
     
         13 . The combinatorial library of  claim 11  wherein the orthogonal S-protecting group is S-thio-butyl, acetamidomethyl, 4-methoxytrityl, S-sulfonate or 3-nitro-2-pyridinesulfenyl.  
     
     
         14 . The combinatorial library of  claim 11  wherein the structural diversity occurs in the metal ion-binding domain or alternatively occurs outside the metal ion-binding domain.  
     
     
         15 . The solid phase combinatorial library of  claim 11  wherein the at least one amino acid residue containing at least one S wherein the said S is protected by an orthogonal S-protecting group is an L- or D-3-mercapto amino acid, including but not limited to L- or D-cysteine or L- or D-penicillamine; 3-mercapto phenylananine; 2-mercaptoacetic acid; 3-mercaptopropionic acid; 2-mercaptopropionic acid; 3-mercapto-3,3,-dimethyl propionic acid; 3-mercapto-3,3,-diethyl proprionic acid; 3-mercapto,3-methyl propionic acid; 2-mercapto,2-methyl acetic acid; 3-cyclopentamethlene,3-mercaptopropionic acid; or 2-cyclopentamethlene,2-mercaptoacetic acid.  
     
     
         16 . A combinatorial library targeted to opioid receptors of different sequence peptidomimetic members synthesized on solid phase, where each constituent library member comprises: 
 (a) a peptidomimetic sequence of a combination of three or more amino acid residues and mimics of amino acid residues bound to solid phase characterized by (i) a sequence of two or more amino acid residues, mimics of amino acid residues or combinations thereof forming a metal ion-binding domain and including at least one amino acid residue or mimic of an amino acid residue containing at least one S wherein the said S is protected by an orthogonal S-protecting group, (ii) a sequence of one or more amino acid residues, mimics of amino acid residues or combinations thereof at the N- or C-terminus of the metal ion-binding domain, or at both the N- and C-terminus of the metal ion-binding domain, and (iii) a cleavable bond attaching the peptidomimetic sequence to solid phase, wherein each peptidomimetic sequence comprises a phenol moiety and a phenyl moiety; and    (b) a unique selection or sequence of amino acid residues, mimics of amino acid residues or combinations thereof in the peptidomimetic sequence of at least one of the constituent members of the library;    wherein the orthogonal S-protecting group may be removed without cleaving the peptidomimetic sequence from the solid phase.    
     
     
         17 . The combinatorial library of  claim 16  wherein the metal ion-binding domain further comprises at least one N available for binding to a metal ion upon removal of the orthogonal S-protecting group, and preferably comprises three residues forming an N 3 S, ligand.  
     
     
         18 . The combinatorial library of  claim 16  wherein the orthogonal S-protecting group is S-thio-butyl, acetamidomethyl, 4-methoxytrityl, S-sulfonate or 3-nitro-2-pyridinesulfenyl.  
     
     
         19 . The combinatorial library of  claim 16  wherein the structural diversity occurs in the metal ion-binding domain or alternatively occurs outside the metal ion-binding domain.  
     
     
         20 . The combinatorial library of  claim 16  wherein the at least one amino acid residue or mimic of an amino acid residue containing at least one S wherein the said S is protected by an orthogonal S-protecting group is an L- or D-3-mercapto amino acid, including but not limited to L- or D-cysteine or L- or D-penicillamine; 3-mercapto phenylananine; 2-mercaptoacetic acid; 3-mercaptopropionic acid; 2-mercaptopropionic acid; 3-mercapto-3,3,-dimethyl propionic acid; 3-mercapto-3,3,-diethyl proprionic acid; 3-mercapto,3-methyl propionic acid; 2-mercapto,2-methyl acetic acid; 3-cyclopentamethlene,3-mercaptopropionic acid; or 2-cyclopentamethlene,2-mercaptoacetic acid.