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-Cys34 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 Cys34 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 Cys34 oxidative modifications and demonstrate for the first time that albumin is a homocysteine and cysteinylglycine vehicle inside the plaque environment.