Partial purification of a beef adrenal Δ5-3-ketosteroid isomerase and studies of its mechanism of action

S. Murota; C. C. Fenselau; Paul Talalay

doi:10.1016/S0039-128X(71)80113-7

Partial purification of a beef adrenal Δ⁵-3-ketosteroid isomerase and studies of its mechanism of action

S. Murota, C. C. Fenselau, Paul Talalay

Research output: Contribution to journal › Article › peer-review

23 Scopus citations

Abstract

The mechanism of isomerization of Δ⁵-androstene-3,17-dione to Δ⁴-androstene-3,17-dione has been examined with partially fractionated preparations of Δ⁵-3-ketosteroid isomerase (EC 5.3.3.1) of beef adrenal microsomes. The enzyme is considerably more active at pH 9.0 than at pH 7.0. Studies on the mechanism of the enzymatic isomerization in D₂O indicate that the reaction proceeds without significant isotope exchange between the medium and the steroid, and that it probably involves an intramolecular (or possibly an intermolecular) proton transfer from C-4 to C-6 in analogy with the Δ⁵-3-ketosteroid isomerase of Pseudomonas testosteroni. Possible reasons for the contrary results obtained by other investigators are discussed.

Original language	English (US)
Pages (from-to)	25-37
Number of pages	13
Journal	Steroids
Volume	17
Issue number	1-5
DOIs	https://doi.org/10.1016/S0039-128X(71)80113-7
State	Published - 1971
Externally published	Yes

ASJC Scopus subject areas

Biochemistry
Molecular Biology
Endocrinology
Pharmacology
Clinical Biochemistry
Organic Chemistry

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10.1016/S0039-128X(71)80113-7

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title = "Partial purification of a beef adrenal Δ5-3-ketosteroid isomerase and studies of its mechanism of action",

abstract = "The mechanism of isomerization of Δ5-androstene-3,17-dione to Δ4-androstene-3,17-dione has been examined with partially fractionated preparations of Δ5-3-ketosteroid isomerase (EC 5.3.3.1) of beef adrenal microsomes. The enzyme is considerably more active at pH 9.0 than at pH 7.0. Studies on the mechanism of the enzymatic isomerization in D2O indicate that the reaction proceeds without significant isotope exchange between the medium and the steroid, and that it probably involves an intramolecular (or possibly an intermolecular) proton transfer from C-4 to C-6 in analogy with the Δ5-3-ketosteroid isomerase of Pseudomonas testosteroni. Possible reasons for the contrary results obtained by other investigators are discussed.",

author = "S. Murota and Fenselau, {C. C.} and Paul Talalay",

note = "Funding Information: Acknowledgments. These studies were supported by National Institutes of Health grants AM 07422, GM 16492 and by the Gustavus and Louise Pfeiffer Foundation of New York.",

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T1 - Partial purification of a beef adrenal Δ5-3-ketosteroid isomerase and studies of its mechanism of action

AU - Murota, S.

AU - Fenselau, C. C.

AU - Talalay, Paul

N1 - Funding Information: Acknowledgments. These studies were supported by National Institutes of Health grants AM 07422, GM 16492 and by the Gustavus and Louise Pfeiffer Foundation of New York.

PY - 1971

Y1 - 1971

N2 - The mechanism of isomerization of Δ5-androstene-3,17-dione to Δ4-androstene-3,17-dione has been examined with partially fractionated preparations of Δ5-3-ketosteroid isomerase (EC 5.3.3.1) of beef adrenal microsomes. The enzyme is considerably more active at pH 9.0 than at pH 7.0. Studies on the mechanism of the enzymatic isomerization in D2O indicate that the reaction proceeds without significant isotope exchange between the medium and the steroid, and that it probably involves an intramolecular (or possibly an intermolecular) proton transfer from C-4 to C-6 in analogy with the Δ5-3-ketosteroid isomerase of Pseudomonas testosteroni. Possible reasons for the contrary results obtained by other investigators are discussed.

AB - The mechanism of isomerization of Δ5-androstene-3,17-dione to Δ4-androstene-3,17-dione has been examined with partially fractionated preparations of Δ5-3-ketosteroid isomerase (EC 5.3.3.1) of beef adrenal microsomes. The enzyme is considerably more active at pH 9.0 than at pH 7.0. Studies on the mechanism of the enzymatic isomerization in D2O indicate that the reaction proceeds without significant isotope exchange between the medium and the steroid, and that it probably involves an intramolecular (or possibly an intermolecular) proton transfer from C-4 to C-6 in analogy with the Δ5-3-ketosteroid isomerase of Pseudomonas testosteroni. Possible reasons for the contrary results obtained by other investigators are discussed.

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Partial purification of a beef adrenal Δ⁵-3-ketosteroid isomerase and studies of its mechanism of action

Abstract

ASJC Scopus subject areas

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