Non-enzymatic glycation and oxidative modifications of proteins has been implicated in the etiology of numerous diseases, including diabetes mellitus. There are irrefutable evidences that human serum albumin (HSA) represents the major and predominant circulating antioxidant in plasma. Under pshysiological conditions HSA mainly exists as form with free thiol groups, which are known to be very sensitive to oxidation. Diabetes is a state of chronic hyperglycaemia coexisting with oxidative damage in tissues and deficyte in antioxidant defence system. We noticed that plasma albumin from patients with diabetes has impaired abilities to bind exogenous cobalt (as it was observed in plasma from patients with myocardial ischemia), which indicates on molecular changes of HSA induced by oxidative stress. To confirm this findings we also examined thiol and carbonyl groups content, AGE and AOPP concentration as endogenous markers of glycooxidation processes. It turned out that level of thiol groups is lower in comparison to healthy subjects, while the other parameters were significantly higher. As protein modification is thought to be important mortality risk factor in diabetic vascular complications, examination of influence of long-term glycation and oxidation or both is fundamental to understand pathomechanism of biochemical disturbances in diabetes and should be helpful in appropriate diagnosis and clinical treatment. The present work aimed to investigate “in vitro” how intensity and period of duration of simulated glycation and oxidation affect on structure of human serum albumin and its antioxidant properties. Glycation was performed by incubation of HSA with diffrent concentrations of D-glucose, followed with oxidation by chloramine T. The glycation-mediated modifications and the free radical-induced conformational changes of HSA were monitored in regular periods by high-performance liquid chromatography (HPLC) and previously mentioned assays. Our data show that the degree of changes in HSA increases depending on the intensity of glycooxidation processes, what reflects in reduced binding of cobalt ions to albumin. In this context structural modifications of human serum albumin seem to be reliable marker of vascular complications in diabetes caused by oxidative stress.

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