Structural madification of erythrocyte membranes under oxidative stress and activity of membrane-bound NADH - methemoglobin reductase

摘要

The activity of NADH-methemoglobin reductase (metHb-reductase) in membranes isolated from human erythrocytes treated with phenylhydrazine at its sublytic concentration was studied. A decrease in the activity of membrane-bound metHb-reductase was shown to depend on the concentration of phenylhydrazine. Simultaneosly, an increase in the level of membrane-bound methemoglobin and a change in the fluorescence parameters of membrane-bound 4, 4'-diisothiocy-anatostibene-2, 2'-disulfonic acid were registered. In the case when Hb-free erythrocyte ghosts were treated with 0.2-2.0 mM phenylhydrazine, the activity of metHb-resuctase did not change. The obtained results indicate that the inhibition of the activity of menbrane-bound metHb-reductase by phenlhydrazine-induced oxidative stress in human erythrocytes is not caused by the direct action of the oxidant on the enzyme. The reason for this is the interaction of the product of hemolgobino xidation with erythrocyte membrane (protein band 3) and structural changes in membrane proteins.