title: Hydroxylation of DHEA and its analogues by Absidia coerulea AM93. Can an inducible microbial hydroxylase catalyze 7α- and 7β-hydroxylation of 5-ene and 5α-dihydro C19-steroids?
abstract: In this paper we focus on the course of 7-hydroxylation of DHEA, androstenediol, epiandrosterone, and 5α-androstan-3,17-dione by Absidia coerulea AM93. Apart from that, we present a tentative analysis of the hydroxylation of steroids in A. coerulea AM93. DHEA and androstenediol were transformed to the mixture of allyl 7-hydroxy derivatives, while EpiA and 5α-androstan-3,17-dione were converted mainly to 7α- and 7β-alcohols accompanied by 9α- and 11α-hydroxy derivatives. On the basis of (i) time course analysis of hydroxylation of the abovementioned substrates, (ii) biotransformation with resting cells at different pH, (iii) enzyme inhibition analysis together with (iv) geometrical relationship between the C-H bond of the substrate undergoing hydroxylation and the cofactor-bound activated oxygen atom, it is postulated that the same enzyme can catalyze the oxidation of C7-Hα as well as C7-Hβ bonds in 5-ene and 5α-dihydro C19-steroids. Correlations observed between the structure of the substrate and the regioselectivity of hydroxylation suggest that 7β-hydroxylation may occur in the normal binding enzyme-substrate complex, while 7α-hydroxylation-in the reverse inverted binding complex.
authors.affiliation: Department of Chemistry, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland.
authors.forename: Natalia
authors.initials: N
authors.lastname: Milecka-Tronina
authors.affiliation: Department of Chemistry, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland.
authors.forename: Teresa
authors.initials: T
authors.lastname: Kołek
authors.affiliation: Department of Chemistry, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland.
authors.forename: Alina
authors.initials: A
authors.lastname: Swizdor
authors.affiliation: Department of Chemistry, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland. Electronic address: anna.szpineter@up.wroc.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Panek
mesh_terms: D020095:Absidia / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism*; D055162:Biocatalysis; D003687:Dehydroepiandrosterone / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D015394:Molecular Structure; D013256:Steroids / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D013256:Steroids; D003687:Dehydroepiandrosterone; D006899:Mixed Function Oxygenases
keywords: Absidia coerulea; DHEA metabolism; Dehydroepiandrosterone 7-hydroxylase; Enzymatic steroid hydroxylation; Hydroxy-DHEA; Hydroxy-epiandrosterone