Open Access
Molecular and enzymatic properties of 7α-hydroxysteroid dehydrogenase from Pseudomonas sp. B-0831
Shigeru Ueda,Masayuki Oda,Shigeyuki Imamura,Masatake Ohnishi +3 more
- Vol. 4, Iss: 1, pp 33-38
TLDR
A novel 7α-hydroxysteroid dehydrogenase (7α-HSD) was purified from Pseudomonas sp.Abstract:
A novel 7α-hydroxysteroid dehydrogenase (7α-HSD) was purified from Pseudomonas sp. B-0831. The molecular weight of the purified enzyme was 25 k on SDS-PAGE and 108 k on gel filtration analysis, suggesting that the enzyme exists as a tetramer of an identical subunit, similar to those of 7α-HSD from E. coli HB101 and Eubacterium sp. VPI 12708. 7α-HSD from P. sp. B-0831 showed high NAD + -dependence and was able to catalyze the oxido-reduction of 7α-hydroxy bile acids including glycine and taurine conjugates. The Km value for cholic acid was determined to be 0.25 mM, which is similar to that for chenodeoxycholic acid and is about four times smaller than those for the conjugates of cholic acid. The kcat values for the conjugates were determined to be about 60-70% of that for free cholic acid. In addition to NAD + , 7α-HSD from P. sp. B-0831 can utilize thio-NAD + to the same extent.read more
Citations
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Journal ArticleDOI
Enzymatic routes for the synthesis of ursodeoxycholic acid.
TL;DR: In this article, a review of multi-step reaction systems for the synthesis of ursodeoxycholic acid is presented, which is used as a secondary bile acid for the treatment of various liver diseases.
Journal ArticleDOI
Cloning, expression and characterization of a putative 7alpha-hydroxysteroid dehydrogenase in Comamonas testosteroni.
TL;DR: A 7α-HSD knock-out mutant of C. testosteroni was constructed and the results showed that 7 α- HSD is involved in steroid degradation.
Journal ArticleDOI
The catalytic promiscuity of a microbial 7α-hydroxysteroid dehydrogenase. Reduction of non-steroidal carbonyl compounds.
TL;DR: A thermostable 7α-hydroxysteroid dehydrogenase from B. fragilis might play multiple functional roles in biosynthesis and metabolism of bile acids, and in the detoxification of xenobiotics containing carbonyl groups in the large intestine, and its broad substrate spectrum offers great potential for finding applications.
Journal ArticleDOI
Enhanced activity and substrate tolerance of 7α-hydroxysteroid dehydrogenase by directed evolution for 7-ketolithocholic acid production
TL;DR: A directed evolution strategy combined with high-throughput screening was applied to improve the catalytic efficiency and tolerance of high substrate concentrations of NADP+-dependent 7α-HSDH from Clostridium absonum, and the best mutant (7α-3) showed significantly enhanced tolerance in the presence of high concentrations of substrate.
Steady-state kinetic properties of 3α-hydroxysteroid dehydrogenase from Pseudomonas sp. B-0831: Steroid substrate specificity and nucleotide cofactor dependency
TL;DR: The results suggest that the enzyme is adaptable to various substrates and cofactors, thus generating the broad substrate specificity with each different reaction mode.
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Crystal structures of the binary and ternary complexes of 7 alpha-hydroxysteroid dehydrogenase from Escherichia coli.
Nobutada Tanaka,Takamasa Nonaka,Tetsurou Tanabe,Tadashi Yoshimoto,Daisuke Tsuru,Yukio Mitsui +5 more
TL;DR: A new catalytic mechanism possibly common to all the enzymes belonging to the SDR family is proposed in which a tyrosine residue acts as a catalytic base and a serine residue plays a subsidiary role of stabilizing substrate binding.
Journal ArticleDOI
Cloning and sequencing of the 7 alpha-hydroxysteroid dehydrogenase gene from Escherichia coli HB101 and characterization of the expressed enzyme
Tadashi Yoshimoto,H Higashi,Akio Kanatani,X S Lin,H Nagai,Hiroshi Oyama,K Kurazono,Daisuke Tsuru +7 more
TL;DR: The 7 alpha-hydroxysteroid dehydrogenase gene from Escherichia coli HB101 was cloned and expressed in E. coli DH1 and the mature enzyme protein-encoding sequence was found to start at a GTG initiation codon and to comprise 765 bp, as judged by comparison with the protein sequence.