S-acylation of fully deprotected peptides using thioesters as acyl donors

Abstract

Diverse eukaryotic proteins require the post-translational addition of S-acyl chains to cysteine residues for proper function, a process known as S-palmitoylation, or S-acylation. To study the effects of this lipid moiety, various complex methods have been developed for the preparation of synthetic lipopeptides. In order to facilitate this task, a novel technique employing readily-prepared long-chain acyl thioesters has been devised. Using S-phenylmercapto-palmitoyl thioester as well as other acyl thioesters, the fluorescent-labeled peptide, myristoyl-GCG-caBim, was S-acylated to high stoichiometry at halftimes as short as 20 min. (initial rate of S-acylation of 179.8 +/- 24.7%/hr) in homogeneous solution, without the presence of micelles or vesicles. The chemical reaction occurred regioselectively on cysteine side-chains without modification of serine or lysine derivatives of the peptide. This method was also utilized to selectively S-acylate the fully deprotected Po peptide, IRYCWLRR-NH2. Such an innovative technique should provide a useful scheme for the general synthesis of S-acylated peptides