Kinetic studies on 15-hydroxyprostaglandin dehydrogenase from human placenta.

The enzyme system 15-hydroxyprostaglandin dehydrogenase, which catalyzes the oxidation of the 15-hydroxy group of all naturally occurring prostaglandins, has been purified 1,270-fold by isoelectric focusing. Km values have been determined for prostaglandin E2 and NAD+ and were found to be 1 and 44 muM. The overall forward reaction was V1 = 450 nmol/min. Both the product 15-ketoprostaglandin E2 and the metabolite 13,14-dihydro-15-ketoprostaglandin E2 were noncompetitive inhibitors for the enzyme.