Effect of Various Parameters on Homocysteinylation of Hemeproteins

Abstract

Elevated levels of homocysteine (Hcy) have been associated with various diseases and conditions. Homocysteine thiolactone (HCTL) is a metabolite of Hcy and reacts with amine groups in proteins to form stable amides, Homocysteinylated proteins. It has been proposed that proteins N-Homocysteinylation contributes to the cytotoxicity of elevated Hcy. In vitro, addition of HCTL to purified proteins has a considerable effect on aggregation state, protein functions and protein structure. For example, N-homocysteinylation causes aggregation of many proteins, such as low-density lipoprotein, fibrinogen and RNase. In the present study the structural properties and aggregation propensity of Hemeproteins were studied in the presence of increasing concentration of HCTL, using different spectroscopic techniques. As shown in this study, HCTL induces gross structural alterations and subsequently aggregation of Hemeprotein in a dose dependent manner. It was also observed that Protein loses its structure and function when it is in contact with homocysteine thiolactone.