FREE-RADICALS INDUCE REVERSIBLE MEMBRANE-CYTOPLASM TRANSLOCATION OF GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE IN HUMAN ERYTHROCYTES

We investigated the role of oxygen free radicals in the modulation of glyceraldehyde-3-phosphate dehydrogenase binding to the erythrocyte me mbrane. Previous studies have demonstrated that in vitro tyrosine phos phorylation of Band 3 prevents the binding of various glycolytic enzym es to its cytoplasmic domain. Since these enzymes are inhibited in the ir bound state, the functional consequence of Band 3 tyrosine phosphor ylation in red blood cells should be to increase glycolysis. To genera te free radicals, we used an azocompound, the hydrophilic 2,2'-azobis( 2-amidinopropane) hydrochloride, which, at 37 degrees C and in the pre sence of oxygen, decomposes and produces peroxyl radicals at at consta nt rate. The reaction of peroxyl radicals with intact red cells induce d a time-dependent loss of the membrane-bound glycolytic enzyme, glyce raldehyde-3-phosphate dehydrogenase, associated with a concomitant dec rease in enzyme activity. At the same time, Band 3 was phosphorylated in tyrosine. These results were completely reversible in plasma after removal of the oxidative stress. The peroxyl radicals also enhanced th e production of lactate in intact cells. Our data reveal a powerful me chanism of erythrocyte metabolic regulation that can boost or reduce e nergy production in times of special need such as during a free radica l attack. (C) 1995 Academic Press, Inc.