Formation of prostaglandin E 1 from 15-ketoprostaglandin E 1 by guinea pig lung 15-hydroxyprostaglandin dehydrogenase

Abstract

Partially purified NAD+-linked 15-hydroxyprostaglandin dehydrogenase from guinea pig lung was found to catalyze the backward reaction, i.e. reduction of 15-ketoprostaglandin E1 to physiologically active prostaglandin E1. The backward reaction was dependent on the presence of NADH and showed an optimum pH at 5.5 while the optimum pH of the forward reaction was 8.8 or higher. The apparent Km for 15-keto-PGE1 was 52 μM while that for PGE1 was 10 μM. The forward and backward reaction rates were lowered to the same extents by partial heat inactivation of the enzyme or by the addition of p-chloromercuribenzoate.