Mika Hayano

Some observations of the Δ1-dehydrogenation of steroids by Bacillus sphaericus

A study of the Δ1-dehydrogenation of steroids by intact cells and cell-free preparations of Bacillus sphaericus (ATCC 7055) has been made. The catalysis comprises of two phases, first a reversible reaction where a rapid exchange of the hydrogens of C-1α and C-2 of the steroid substrate occurs with the hydrogen of the medium, and the second, the essentially irreversible formation of the Δ1 bond. Examination of these two phases with the use of tritium-labelled steroids and tritium oxide-enriched water has been made. Various electron acceptors have been tested with a cell-free preparation of Δ1-dehydrogenase and it has been shown that substances with the quinone structure are highly effective.

Oxygenases in Lipid and Steroid Metabolism

Publisher Summary Lipids are a class of compounds composed of many and diverse members. Among these, only the group of fatty acids and steroids, which comprise the sterols, bile acids, sex hormones, and adrenal cortical hormones, provide substrates for oxygenase activity. This chapter discusses the oxygenases in lipid and steroid metabolism. Only three oxygenases were found in the fatty acid category: (1) lipoxidase, which performs the hydroperoxidation of unsaturated fatty acids, (2) long chain fatty acid peroxidase, which catalyzes the α-oxidation and decarboxylation of C12–C18 fatty acids, and (3) a fatty acid hydroxylase, which initiates a two-step reaction resulting in the formation of a monounsaturated fatty acid. Some generalizations can be made concerning oxygenases that act on steroids. In the biosynthesis of cholesterol from acetate and its multiples, hydroxylases do not participate until the conversion of the squalene chain to lanosterol. The chapter describes the syntheses of biologically important steroids with an emphasis on the steps where oxygenases take part.

Conversion of hydroxytyramine to norepinephrine-like material☆

In the biosynthesis of norepinephrine (NE), one likely reaction is oxidation of the P-carbon in the side chain of the various candidates for precursor. This reaction is an oxidation with the formation of a secondary alcohol group. Various aspects of this reaction are discussed by Heard and Raper (1) who were concerned with the oxidation of 3,4-dihydroxyphenyl-N-methylalanine with respect to it,s possible role as a precursor of adrenaline. Studies which attempted to investigate the conversion of various possible precursors when incubated with adrenal medullary tissue indicated that tyramine, phenylethylamine, phenylalanine, and hydroxytyramine (HT) gave positive results (2-5). However, in each of these studies, the calorimetric methods used are not beyond criticism. More recently, Demis, Blaschko, and Welch have reported t’he conversion of 3,4-dihydroxyphenylalanine-Cl* (dopa) to IKE when incubated with medullary homogenates (6). We wish to report our studies on the conversion of HT to norepinephrine-like material (HELM) by beef adrenal acetone powder and several species of molds.

The Epoxidation of Unsaturated Steroids

Data for several additional instances of epoxidation by biological systems at isolated unsaturated sites on steroid structures are presented.These systems include the bovine adrenal, Curvularia lunata and a Curvularia species. This reaction predictably occurred only in the presence of enzymes capable of introducing “axial” hydroxyl functions at saturated carbons of corresponding analogous structures. A discussion of the implication of these findings in terms of the mechanism of the enzymatic hydfoxylation reaction is given.

The catalytic reduction of 3β-hydroxyandrost-5-en-17-one with tritium. The distribution and orientation of label in the product ☆

Abstract 3β-Hydroxyandrost-5-en-17-one (I) was reduced catalytically with carrier-free tritium. The product was mainly 3β-hydroxy-5α-androstan-17-one (II), which was converted to androst-4-ene-3, 17-dione (VI) with a loss of 43% of the label. 6β-Bromination and 6β-methoxylation was carried out on VI with little loss of label, indicating that the tritium at C-6 was alpha orientated. Chemical and kinetic experiments established that the additional label was at C-7α. The distribution of tritium in the reduced product II was 43% 5α, 35% 6α and 22% 7α.

The preparation and properties of 20β-hydroxysteroid dehydrogenase of Curvularia lunata

Abstract 17α,20β,21-Trihydroxypregn-4-ene-3-one has been identified as being formed from Compound S in a cell-free system prepared from C . lunata . 17α,20β,21-Trihydroxypregn-4-ene-3-one was separated from its 20α epimer by paper chromatography and differentiated from it by its infra-red spectrum. The 20β-hydroxysteroid dehydrogenase activity can be enhanced by adaptation, is precipitated between 40% and 60% saturation with ammonium sulphate and requires NADPH2 as co-factor.

Some Aspects of Stereoselectivity in the Introduction of Tritium into Steroids

The continuous increase in the use of radioisotopes as tracers for biological reactions and pathways renders imperative the exact determination of label position and label stability. The following examples represent typical cases involving isotopic substitution outside as well as within† the reaction center.

The C-20α reduction of steroids by hog liver preparations

Abstract The presence of a steroid C-20α-reductase has been demonstrated in hog liver brei by the isolation and identification of Δ 4 -pregnene-20α, 21-diol-3-one and Δ 4 -pregnene-17α, 20α, 21-triol-3-one after the incubation of 11-deoxycorticosterone and 11-deoxycortisol, respectively. Some properties of the 20α-reductase are described.

A Comparison of Infrared Frequencies of 19-Nor Steroids and their 19-Methyl Analogues

The infrared absorption spectra of thirteen 19-nor steroids in the C-19 series were recorded by the potassium bromide dispersal technique It was found that a shift to higher frequencies occurred for the bands that have been correlated with structures in saturated 3-hydroxysteroids, 3α, 5α shifted from 998 to 1017 cm−1, 3β, 5α from 1042 to 1060 cm−1, 3α, 5β from 1035 to 1060 cm−1, and 3β 5β from 1033 to 1055 cm−1. A band near 881 cm−1 helped identify Δ4-19-nor structures, while a similar band near 885 and/or 825 cm−1 seemed characteristic for the Δ1-19-nor compound