The kinetic mechanism of the hypothalamic progesterone 5α-reductase

摘要: Abstract The kinetic mechanism of the hypothalamic NADPH-linked progesterone 5α-reductase from female rats was determined to be equilibrium ordered sequential by initial velocity, product inhibition and dead-end studies. Analysis velocity data resulted in intersecting double reciprocal plots indicating a (apparent K m (progesterone) = 95.4 ± 4.5 nM; apparent ia (NADPH) 9.9 0.7±M). plot l/v vs l/progesterone intersected on ordinale which is consistent with an mechanism. Ordered addition substrates also supported studies NADP versus NADPH progesterone. competitive inhibitor 4.3 1.3μM) noncompetitive 31.9 1.4μM ii 145.4 15.5μM). These patterns show that binds prior Taken together, these analyses indicate cofactor, NADPH, enzyme rapid preferentially precedes binding