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A novel olefinic rearrangement. The enzymic conversion of cholesta-7,9-dien-3 -ol into cholesta-8,14-dien-3 -ol.

ABSTRACT: 1. [3alpha-(3)H]Cholesta-7,9-dien-3beta-ol is converted in high yield into cholesterol by a 10000g(av.) supernatant fraction of rat liver homogenate. 2. Incubation of cholesta-7,9-dien-3beta-ol with [4-(3)H]NADPH and rat liver microsomal fractions under anaerobic conditions resulted in (3)H being incorporated into the 14alpha-position of cholest-7-en-3beta-ol. 3. Under anaerobic conditions in the absence of NADPH cholesta-7,9-dien-3beta-ol was isomerized into cholesta-8,14-dien-3beta-ol by rat liver microsomal fractions.

SUBMITTER: Akhtar M

PROVIDER: S-EPMC1174072 | biostudies-other | 1972 Sep

REPOSITORIES: biostudies-other

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The role of a cholesta-8,14-dien-3-beta-ol system in cholesterol biosynthesis.

Project description:The biosynthesis of cholesterol from squalene and tritiated water is described. Degradation of the cholesterol indicated that C-15 may be involved in cholesterol biosynthesis. In accordance with this view it is shown that in the conversion of [2RS-(3)H(2)]mevalonic acid into cholesterol one of the hydrogen atoms at C-15 is removed. A mechanism for the removal of the 14alpha-methyl group in steroid biosynthesis that involves the labilization of a C-15 hydrogen atom is outlined. In accordance with the requirement of this scheme it is shown that 4,4'-dimethyl-cholesta-8,14-dien-3beta-ol is converted into cholesterol.

| S-EPMC1187605 | biostudies-other

Mode of formulation of cholesta-5,7-dien-3beta-ol from Cholest-5-en-3beta-ol by Larvae of Calliphora erythrocephala.

Project description:1. The conversion of cholest-5-en-3beta-ol (cholesterol) into cholesta-5,7-dien-3beta-ol by axenic Calliphora erythrocephala larvae was demonstrated. 2. The transformation is probably direct (Delta(5)-->Delta(5,7)) and does not involve a Delta(0) intermediate (Delta(5)-->Delta(0)-->Delta(7)--> Delta(5,7)). 3. Delta(7)-bond formation involves the stereospecific elimination of the 7beta hydrogen atom. 4. The relative amounts of free and esterified sterols were determined in larvae grown on cholesterol as sole sterol source and on 5alpha-cholestan-3beta-ol supplemented with minimal amounts of cholesterol. 5. The significance of the results is assessed in relation to the probable role of cholesta-5,7-dien-3beta-ol as an intermediate in the biosynthesis of ecdysones.

| S-EPMC1172472 | biostudies-other

A novel labda-7,13e-dien-15-ol-producing bifunctional diterpene synthase from Selaginella moellendorffii.

Project description: Not available

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The metabolism of the fluorescent probe cholesta-5,7,9(11)-trien-3 beta-ol by rat liver.

Project description:The chemical synthesis and metabolism of [3alpha-(3)H]cholesta-5,7,9(11)-trien-3beta-ol is described. This radioactive fluorescent sterol probe cannot be rearranged or converted to cholesterol by rat liver but is readily esterified.

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(1S*,3S*,8S*,10S*)-10-Fluoro-15-oxa-tetra-cyclo-[6.6.1.0.0]penta-deca-5,12-dien-3-ol.

Project description:The title compound, C(14)H(17)FO(2), was obtained from anti-4a,9a:8a,10a-diep-oxy-1,4,4a,5,8,8a,9,9a,10,10a-deca-hydro-anthra-cene via tandem hydrogen-fluoride-mediated epoxide ring-opening and transannular oxacyclization. With the two cyclo-hexene rings folded towards the oxygen bridge, the title tetra-cyclic fluoro-alcohol mol-ecule displays a conformation remin-iscent of a pagoda. The crystal packing is effected via inter-molecular O-H?O hydrogen bonds, which link the mol-ecules into a zigzag chain along the b axis.

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Conversion of (+/-)-synephrine into p-hydroxyphenylacetaldehyde by Arthrobacter synephrinum. A novel enzymic reaction.

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<i>rac</i>-11-Selena-12,13-di-aza-bicyclo-[10.3.0]penta-deca-10a(13a),12-dien-1-ol.

Project description:The title compound, C12H20N2OSe, crystallizes in strands of enanti-omeric mol-ecules connected via O-H⋯N hydrogen bonds. There are only slight deviations from an ideal gauche conformation in the deca-methyl-ene chain, indicating just a little strain.

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Aliphatic C-H to C-C conversion: synthesis of (-)-cameroonan-7?-ol.

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The intermediary role of a steroid 8,14-dien-3-beta-ol system in ergosterol biosynthesis.

Project description:1. A mechanism for the removal of the 14alpha-methyl group in ergosterol biosynthesis that involves the intermediacy of an 8,14-diene system is outlined. 2. In accordance with the requirements of this scheme, it is shown that 5alpha-ergosta-8,14-dien-3beta-ol is converted into ergosterol by Saccharomyces cerevisiae.

| S-EPMC1185083 | biostudies-other

The conversion of cholest-7-en-3beta-ol into cholesterol. General comments on the mechanism of the introduction of double bonds in enzymic reactions.

Project description:Convenient syntheses of 6beta-tritiated Delta(7)-cholestenol and 3alpha-tritiated Delta(7)-cholestene-3beta,5alpha-diol are described. It was shown that the conversion of 6beta-tritiated Delta(7)-cholestenol into cholesterol is accompanied by the complete retention of label. It was unambiguously established that the overall reaction leading to the introduction of the double bond in the 5,6-position in cholesterol occurs via a cis-elimination involving the 5alpha- and 6alpha-hydrogen atoms and that during this process the 6beta-hydrogen atom remains completely undisturbed. Metabolic studies with 3alpha-tritiated Delta(7)-cholestene-3beta,5alpha-diol revealed that under anaerobic conditions the compound is not converted into cholesterol. This observation, coupled with the previous work of Slaytor & Bloch (1965), is interpreted to exclude a hydroxylation-dehydration mechanism for the origin of the 5,6-double bond in cholesterol. It was also shown that under aerobic conditions 3alpha-tritiated Delta(7)-cholestene-3beta,5alpha-diol is efficiently converted into cholesterol and that this conversion occurs through the intermediacy of 7-dehydrocholesterol. Cumulative experimental evidence presented in this paper and elsewhere is used to suggest that the 5,6-double bond in cholesterol originates through an oxygen-dependent dehydrogenation process and a hypothetical mechanism for this and related reactions is outlined.

| S-EPMC1198440 | biostudies-other

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