Purification of dihydropteridine reductase from human platelets

Abstract
Dihydropteridine reductase was purified approximately 1,700-fold from human outdated blood platelets. Two forms of the enzyme, A and B, were resolved. They have the same Km values for 2-amino-6,7,-dimethyl-4-hydroxydihydropteridine (46 μml;M vs 49 μml;M), but the A form has a Km for NADH that is two times higher than that of the B form (20 μml;M vs 9 μml;M).