Article

A cyclodecapeptide ligand to vitamin B12.

Département de Chimie Moléculaire-UMR-CNRS 5250 & ICMG FR 2607, Université Joseph Fourier, BP 51, 38041, Grenoble Cedex 9, France.
Organic & Biomolecular Chemistry (impact factor: 3.7). 12/2008; 6(22):4134-41. DOI:10.1039/b811234g pp.4134-41
Source: PubMed

ABSTRACT Libraries of cyclic decapeptides were screened with vitamin B(12) derivatives to give cyclic peptide ligands incorporating histidine and cysteine as coordinating residues and negatively charged amino acids. Two hits, cyclo-(HisAspGluProGlyIleAlaThrProdGln) and cyclo-(ValAspGluProGlyGluAspCysProdGln) were resynthesized in good yields for solution experiments. The peptides bind aquocobalamin with coordination of His or Cys to the cobalt with high affinities (K(a) approximately 10(5) M(-1)). Additional interactions between the peptide side chains and the vitamin B(12) corrin moiety were determined by studying the (1)H NMR solution structure. The cyclopeptide-cobalamin complex with the histidine residue showed enhanced stability towards cyanide exchange, demonstrating the shielding effect of the ligand on the metal center.

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Keywords

1)H NMR solution structure
 
affinities
 
amino acids
 
cyanide exchange
 
cyclic decapeptides
 
cyclic peptide ligands incorporating histidine
 
cyclopeptide-cobalamin complex
 
good yields
 
histidine residue
 
ligand
 
peptide side chains
 
peptides bind aquocobalamin
 
shielding effect