Human Serum Albumin Cys34 Oxidative Modifications following Infiltration in the Carotid Atherosclerotic Plaque

OBJECTIVES To evaluate if the prooxidant environment present in atherosclerotic plaque may oxidatively modify filtered albumin. METHODS Fluorescein-5-maleimide labelled plasma samples and plaque extracts from 27 patients who had undergone carotid endarterectomy were analysed through nonreducing SDS-PAGE for albumin-Cys(34) oxidation. Furthermore, degree and pattern of S-thiolation in both circulating and plaque-filtered albumin were assayed. RESULTS Albumin filtered in the atherosclerotic plaque showed higher levels of Cys(34) oxidative modifications than the corresponding circulating form as well as different patterns of S-thiolation. CONCLUSIONS Data indicate that the circulating albumin, once filtered in plaque, undergoes Cys(34) oxidative modifications and demonstrate for the first time that albumin is a homocysteine and cysteinylglycine vehicle inside the plaque environment.