[NAD+-dependent 15-hydroxyprostaglandin dehydrogenase from the human term placenta].

A NAD+-dependent 15-hydroxyprostaglandin dehydrogenase was purified from human term placenta using monoclonal antibody-coupled Sepharose affinity chromatography. The monoclonal antibodies were prepared against the molecule which was purified according to the method of Jarabak et al. About 4,800-fold purification was achieved with a 3% yield. The highest specific activity was 1,890 mU/mg. The molecular weight of the enzyme determined by gel filtration was 49,000. Polyacrylamide gel electrophoresis of the purified enzyme revealed the presence of two protein bands which were thought to be derived from the same enzyme molecule. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed two main bands of which the molecular weights were 28,000 to 30,000 and 52,000 to 56,000. Electrophoretic analyses suggest a labile oligomeric structure that may relate to the instability of the enzyme activity, which contradicts the monomer theory reported by Jarabak et al.