Author/Editor     Zorko, Matjaž; Gottlieb, HE; Žakelj-Mavrič, Marija
Title     Pluripotency of 17beta-hydroxysteroid dehydrogenase from the filamentous fungus Cochliobolus lunatus
Type     članek
Source     Steroids
Vol. and No.     Letnik 65
Publication year     2000
Volume     str. 46-53
ISSN     0039-128X
Language     eng
Abstract     Cochliobolus lunatus 17B-hydroxysteroid dehydrogenase (17B-HSD) is pluripotent for several steroidal and nonsteroidal substrates. In the presence of NADPH the enzyme was found to reduce 3-keto groups of 4,5-dihydro steroids, 20-keto groups, and most efficiently,17-keto groups of steroidal substrates. In addition, several quinones were accepted and found to be even better substrates as steroids due to their higher affinity for the enzyme-coenzyme complex and faster conversion of the enzyme-coenzyme-substrate complex into the corresponding products. As suggested by the competition studies quinones and 17-ketosteroids are converted by the same active center of the enzyme. For all tested substrates, the equilibrium ordered mechanism was established with NADPH binding first to the enzyme. According to our knowledge, the investigated 17B-HSD is the first known fungal pluripotent enzyme of this type.
Descriptors     ASCOMYCETES
17-HYDROXYSTEROID DEHYDROGENASES
BINDING SITES
BINDING, COMPETITIVE
NADPH DEHYDROGENASE
KINETICS
SPECTRUM ANALYSIS, MASS
NUCLEAR MAGNETIC RESONANCE
SUBSTRATE SPECIFICITY
STEROIDS
ANDROSTENEDIONE
VITAMIN K
QUINONES