EVIDENCE FOR THE ESSENTIAL ARGININE RESIDUE(S) IN THE CATALYTIC ACTIVITY OF HUMAN ERYTHROCYTE GLUCOSE 6-PHOSPHATE DEHYDROGENASE

Glucose 6-phosphate dehydrogenase from human erythrocyte was inactivaled by butanedione. More than 50% of the enzyme activity was lost by butanedione(lmM) within the first 20 minutes of incubation. The inactivation was protected by the coenzyme NADP+. Glucose 6-phosphale. however, stimulated the enzyme inactivation. Fluorescence studies showed a conformational change in the butanedione-inactivaled enzyme. The data suggest that essential arginine residue(s), probably located in the coenzyme binding site, may be involved in the catalytic activity of the enzyme.