Studies of Oxidant-Induced Changes in Albumin Transport Function with a Fluorescent Probe K-35. Metal-Catalyzed Oxidation

The dynamics of albumin transport function was studied during metal-catalyzed oxidation of albumin in diluted blood plasma from healthy donors and in the solution of purified albumin using fluorescent probe K-35. The changes were compared with the dynamics of free radical oxidation markers. For oxidation, different concentrations of Cu 2+ , Fe 2+ , Fe 3+ ions as well as EDTA and H 2 O 2 were used. Oxidative modification of proteins was assessed by carbonyl and bityrosine fluorescent products. Oxidation of plasma lipids was assessed by the levels of TBA-reactive products. It was found that oxidation markedly decreased effective concentration of albumin characterizing albumin binding capacity, and leads to accumulation of carbonyl products of protein oxidation, bityrosine fluorescent products in proteins, and TBA-active products of lipid oxidation. It was hypothesized that reduced effective concentration of albumin is related to impairment of its binding sites and/or accumulation of free-radical oxidation products filling the binding sites of albumin.