Hypochlorous acid damages erythrocyte membrane proteins and alters lipid bilayer structure and fluidity

Treatment of human erythrocyte membranes with active forms of chlorine (hyp ochlorous acid and chloramine T) resulted in a concentration-dependent inhi bition of the membrane Na+, K+- and Mg2+-ATPases. Membrane protein thiol gr oup oxidation was consistent with inactivation of enzymes and preceded oxid ation of tryptophan residues and chloramine formation. Erythrocyte exposure to hypochlorous acid led to complex changes of cell membrane rigidity and cell morphological transformations: cell swelling, echinocyte formation, an d haemolysis. The inhibition of ion pump ATPases of human erythrocyte membr anes may be due to direct oxidation of essential residues of enzyme (thiol groups) and structural rearrangement of the membrane. (C) 2001 Elsevier Sci ence Inc.