The purification and characterization of a prostacyclin dehydrogenase from rabbit kidney

A highly purified NADP-linked 15-hydroxyprostaglandin (prostacyclin) dehydrogenase has been isolated from rabbit kidney. This enzyme has a molecular weight of 56,000-62,000 and is composed of two subunits which are presumably identical. It is not a flavoprotein. Fluorometric titrations with NADPH revealed that the cofactor was bound to the free enzyme with a dissociation constant of 0.04 microM. The results of kinetic studies were compatible with either a random mechanism or an ordered mechanism with NADP binding first. Although this enzyme oxidizes prostacyclin more rapidly than any other prostaglandin, it reduces 4-nitrobenzaldehyde, phenanthrenequinone, and menadione more rapidly than it oxidizes prostacyclin.