Purification and characterization of a 15-ketoprostaglandin d-reductase from bovine lung
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15-Ketoprostaglandin d-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 the N-terminal amino 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 E (apparent K = 10 µm) is a substrate, in contrast to prostaglandin E. The enzyme was active with both NADH (apparent K = 88-94 µM) and NADH (apparent K = 5-9 µM) 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 E to 15-ketoprostaglandin E. The turnover number of the enzyme was determined to be either 60 or 42 min. 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 d-reductase together with 15-hydroxyprostaglandin dehydrogenase ensures an irreversible catabolism of prostaglandins.
Originalsprog | Engelsk |
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Tidsskrift | Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism |
Vol/bind | 574 |
Udgave nummer | 1 |
Sider (fra-til) | 136-145 |
Antal sider | 10 |
ISSN | 0005-2760 |
Status | Udgivet - 27 jul. 1979 |
ID: 45563183