Purification and characterization of membrane-bound prostaglandin E synthase from bovine heart

Prostaglandin (PG) E synthase was solubilized with 6 mM sodium deoxycholate from the microsomal fraction of bovine hearts. The enzyme was purified by about 800-fold to apparent homogeneity. The specific activity of the purified enzyme was about 830 mU/mg of protein, and the K-m value for PGH(2) was 24 mu M. The molecular weight of the enzyme was about 31 000 on SDS-polyacrylamide gel electrophoresis and was about 60000 by gel filtration. The enzyme was separated from glutathione (GSH) S-transferase by DEAE-Toyopearl column chromatography, and did not exhibit any GSH S-transferase activity towards four different substrates. The purified enzyme was active in the absence of GSH but it: was activated by various SH-reducing reagents including dithiothreitol, GSH, or beta-mercaptoethanol, This is the first reported purification of membrane-bound PGE synthase to apparent homogeneity. (C) 1999 Elsevier Science B.V. All rights reserved.