Homocysteine thiolactone and protein homocysteinylation: mechanistic studies with model peptides and proteins

In vitro incubations were performed to show that homocysteine thiolactone could generate covalent adducts with model peptides and proteins. MS and MS/MS data suggest that the thiolactone reacts with the side-chain amino group of lysine residues as well as with the N-terminal amino group or C-terminal carboxy group. For larger peptides and proteins, the contribution from the E-amino groups of lysine residues should be predominant. These data could help explain the detrimental effects of elevated levels of homocysteine and homocysteine thiolactone. Copyright (C) 2002 John Wiley Sons, Ltd.