The stoichiometry of the conversion of cholesterol and hydroxycholesterols to pregnenolone (3beta-hydroxypregn-5-en-20-one) catalysed by adrenal cytochrome P-450.

Proceedings of the National Academy of Sciences of the United States of America ·Vol. 71 ·No. 4 ·1974-04-00 ·Pages 1441-5

Shikita M, Hall PF

Abstract

The stoichiometry of the side-chain cleavage of cholesterol (cholest-5-en-3beta-ol), 20alpha-hydroxycholesterol (cholest-5-ene-3beta,20alpha-diol), and 20alpha,22-dihydroxycholesterol (cholest-5-ene-3beta,20alpha,22-triol) has been examined with respect to TPNH, oxygen and H(+). Side-chain cleavage of cholesterol can be described by the following equation:Cholesterol + 3TPNH + 3H(+) + 3O(2) --> Pregnenolone (3beta-hydroxypregn-5-ene-20-one) + isocapraldehyde + 3 TPN(+) 4H(2)OStoichiometry of 20 alpha-hydroxycholesterol is 2TPNH and 2O(2) per mole of cleavage and with 20alpha, 22-dihydroxycholesterol the values are 1:1:1. In addition 1 mole of H(+) is consumed per mole of TPNH oxidized in each of these reactions. These observations are in keeping with a mechanism previously proposed in the literature, namely:Cholesterol --> 20alpha-OH-Cholesterol --> 20alpha, 22-di-OH-Cholesterol --> pregnenoloneDiscordant observations are reviewed and it is concluded that insufficient data are available to sustain objections to this pathway.

MeSH Terms

Adrenal Glands/cytology,enzymology Animals Carbon Isotopes Catalysis Cattle Cholesterol/metabolism Cytochrome P-450 Enzyme System/metabolism Ferredoxins/metabolism Hydrogen-Ion Concentration Hydroxylation Mitochondria/enzymology Models, Chemical NADH, NADPH Oxidoreductases/metabolism Oxygen Consumption Pregnenolone/biosynthesis

Chemicals

Carbon Isotopes Ferredoxins Pregnenolone Cytochrome P-450 Enzyme System Cholesterol NADH, NADPH Oxidoreductases

Authors & Affiliations

2 authors, click to expand affiliations / ORCID

Shikita M

Hall P F

References (21)

21 references, click to expand

Cleavage of cholesterol side chain by adrenal cortex. I. Cofactor requirement and product of clevage.
J Biol Chem. 1961 Jan;236:65-7 PMID: 13695144
Cytochrome P-450 from bovine adrenocortical mitochondria: an enzyme for the side chain cleavage of cholesterol. I. Purification and properties.
J Biol Chem. 1973 Aug 25;248(16):5598-604 PMID: 4723901
Transformation of labeled cholesterol, 20-alpha-hydroxycholesterol, (22R)-22-hydroxycholesterol, and (22R)-20-alpha, 22-dihydroxycholesterol by adrenal acetone-dried preparations from guinea pigs, cattle and man.
Steroids. 1970 Jan;15(1):13-60 PMID: 4905214
Improved purification of bovine adrenal iron-sulfur protein.
Biochim Biophys Acta. 1972 Apr 15;263(2):272-8 PMID: 4402303
Studies on the biosynthetic conversion of cholesterol into pregnenolone. Side chain cleavage of a t-butyl analog of 20 -hydroxycholesterol, (20R(-t-butyl-5-pregnene-3 ,20-diol, a compound completely substituted at C-22.
J Biol Chem. 1972 Mar 10;247(5):1462-72 PMID: 5012318
CARBON MONOXIDE-COMBINING SUBSTANCES IN RAT ADRENAL.
Biochim Biophys Acta. 1964 Nov 22;92:415-7 PMID: 14249135
Determination of small amounts of pregnenolone.
Anal Biochem. 1971 Sep;43(1):134-8 PMID: 4331758
Electron transport in relation to steroid biosynthesis. Inhibition of side-chain cleavage of cholesterol by hyperbaric oxygen.
Biochemistry. 1967 Sep;6(9):2794-802 PMID: 4383279
Formation of isocaproaldehyde in the enzymatic cleavage of cholesterol side chain by adrenal extract.
Biochemistry. 1966 May;5(5):1650-2 PMID: 5961284
The cholesterol side-chain cleavage system of bovine adrenal cortex.
Eur J Biochem. 1967 Oct;2(3):275-85 PMID: 6078538
Enzymatic mechanism of steroid hydroxylation.
Science. 1969 Mar 21;163(3873):1297-300 PMID: 4387870
Method of determining oxygen concentrations in biological media, suitable for calibration of the oxygen electrode.
Anal Biochem. 1970 Feb;33(2):390-9 PMID: 4314758
Cytochrome P-450 from bovine adrenocortical mitochondria: an enzyme for the side chain cleavage of cholesterol. II. Subunit structure.
J Biol Chem. 1973 Aug 25;248(16):5605-9 PMID: 4723902
Requirement of NADPH and molecular oxygen for the side-chain cleavage of 20-alpha, 22-xi-dihydroxycholesterol.
Arch Biochem Biophys. 1968 Jun;125(3):1016-7 PMID: 4386446
Fate of molecular oxygen required by endocrine enzymes for the side-chain cleavage of cholesterol.
Biochim Biophys Acta. 1968 Jul 1;152(4):749-57 PMID: 5660089
Sterol metabolism. XVI. Cholesterol 20-alpha-hydroperoxide as an intermediate in pregnenolone biosynthesis from cholesterol.
Biochem Biophys Res Commun. 1970 Aug 11;40(3):510-6 PMID: 4395341
20alpha,22x-Dihydroxycholesterol, an intermediate in the biosynthesis of pregnenolone (3beta-hydroxypregn-5-en-20-one) from cholesterol.
J Biol Chem. 1962 Mar;237:699-702 PMID: 13911962
INHIBITION OF THE BIOSYNTHESIS OF PREGNENOLONE BY 20-ALPHA-HYDROXYCHOLESTEROL.
Biochim Biophys Acta. 1964 Nov 8;93:441-4 PMID: 14251332
The cholesterol side-chain cleavage system of the adrenal cortex: a mixed-function oxidase.
Biochem Biophys Res Commun. 1966 Jul 6;24(1):10-7 PMID: 5966391
The purification and properties of NADPH-adrenodoxin reductase from bovine adrenocortical mitochondria.
FEBS Lett. 1972 Nov 15;28(1):45-7 PMID: 4405223
Spectral properties, respiratory activity, and enzyme systems of bovine corpus luteum mitochondria.
Biochemistry. 1971 Jul 20;10(15):2909-16 PMID: 4398872

Article Info

Journal

Proceedings of the National Academy of Sciences of the United States of America

Abbr.

Proc Natl Acad Sci U S A

ISSN

0027-8424

DOI

10.1073/pnas.71.4.1441

Published

1974-04-00

Pages

1441-5

Language

English

Region

United States

NLM ID

7505876

PMCID

PMC388245

Subset

External Links

PubMed source DOI: 10.1073/pnas.71.4.1441 PMC Full Text View journal details

Analysis Services

The stoichiometry of the conversion of cholesterol and hydroxycholesterols to pregnenolone (3beta-hydroxypregn-5-en-20-one) catalysed by adrenal cytochrome P-450.

Contact

WeChat Official Account