title: Purification and characterization of a 15-ketoprostaglandin delta 13-reductase from bovine lung.
abstract: 15-Ketoprostaglandin delta 13-reductase from bovine lung has been purified using affinity chromatography to apparent homogeneity, as judged from polyacrylamide gel electrophoresis with and without sodium dodecyl sulphate. Valine was identified as tne N-terminal aumino acid, and the isoelectric point was estimated at pH 7.8. Molecular weights of 56,000 and 39,500 were found by the use of gel filtration and SDS-polyacrylamide gel electrophoresis, respectively. The enzyme was found to be specific for the 15-keto group, thus 15-ketoprostaglandin E4 (apparent Km = microM) is a substrate, in contrast to prostaglandin E1. The enzyme was active with both NADH (apparent Km = 88--94 microM) and NADH (apparent Km = 5--9 microM) as coenzyme, but the V max with NADH was more than twice that obtained with NADPH. The enzyme did not catalyze the reversed reaction: 13,14-dihydro-15-keto-prostaglandin E1 to 15-ketoprostaglandin E1. The turnover number of the enzyme was determined to be either 60 or 42 min-1. The low value of the turnover number is compensated by a high concentration (96.4 mU/g tissue) of the enzyme in lung tissue, resulting in a high metabolic capacity. Thus, 15-ketoprostaglandin delta 13-reductase together with 15-hydroxyprostaglandin dehydrogenase ensures an irreversible catabolism of prostaglandins.
mesh_terms: D011452:15-Oxoprostaglandin 13-Reductase / Q000302:isolation & purification*; D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008168:Lung / Q000201:enzymology; D008970:Molecular Weight; D010088:Oxidoreductases / Q000302:isolation & purification*; D011458:Prostaglandins E / Q000378:metabolism*
chemical_list: D011458:Prostaglandins E; D010088:Oxidoreductases; D011452:15-Oxoprostaglandin 13-Reductase