Microsomal enzymes of cholesterol biosynthesis from lanosterol. Characterization, solubilization, and partial purification of NADPH-dependent Δ8,14-steroid 14-reductase

Y. K. Paik, J. M. Trzaskos, A. Shafiee, J. L. Gaylor

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

The membrane-bound enzyme of microsomes that catalyzes NADPH-dependent reduction of the 14-double bond of conjugated Δ8,14- and Δ7,14-sterols has been studied both as collected in microsomes from broken cell preparations of rat liver and after solubilization. Optimal incubation conditions for assay of the membrane-bound enzyme have been determined, and properties of the microsomal enzyme have been established with respect to cofactor requirements, kinetics, pH, addition of inhibitors, addition of glycerol phosphatides, and sterol substrate specificity. The 14-reductase is readily solubilized with a mixture of octylglucoside and taurodeoxycholic acid. The solubilized enzyme has been enriched by precipitation with polyethylene glycol and chromatography on DEAE-Sephacel and hydroxylapatite columns. The resulting partially purified enzyme has been obtained free of other microsomal enzymes of cholesterol biosynthesis: 4-methyl sterol oxidase, Δ5,7-sterol 7-reductase, Δ8,24-sterol 24-reductase, 3-ketosteroid reductase, and steroid 8 → 7-ene isomerase, plus microsomal cytochrome P-450, cytochrome P-450 reductase, cytochrome b5 reductase, and cytochrome b5. The partially purified enzyme is stimulated by addition of phospholipids. All of the properties exhibited by partially purified 14-reductase are consistent with the suggestion that the solubilized and enriched enzyme catalyzes the microsomal reduction of the 14-double bond of the sterol-conjugated dienes. However, presence of the enzyme does not prove that the sterol-conjugated dienes are obligatory precursors of cholesterol.

Original languageEnglish
Pages (from-to)13413-13423
Number of pages11
JournalJournal of Biological Chemistry
Volume259
Issue number21
Publication statusPublished - 1984 Dec 1

Fingerprint

Lanosterol
Biosynthesis
NADP
Purification
Oxidoreductases
Steroids
Cholesterol
Sterols
Enzymes
Cytochromes b5
Microsomes
Phospholipids
Taurodeoxycholic Acid
Cytochrome Reductases
Membranes
Isomerases
NADPH-Ferrihemoprotein Reductase
Durapatite
Substrate Specificity
Chromatography

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

@article{1fff9efc3d434c98af4b9b22cee1a81d,
title = "Microsomal enzymes of cholesterol biosynthesis from lanosterol. Characterization, solubilization, and partial purification of NADPH-dependent Δ8,14-steroid 14-reductase",
abstract = "The membrane-bound enzyme of microsomes that catalyzes NADPH-dependent reduction of the 14-double bond of conjugated Δ8,14- and Δ7,14-sterols has been studied both as collected in microsomes from broken cell preparations of rat liver and after solubilization. Optimal incubation conditions for assay of the membrane-bound enzyme have been determined, and properties of the microsomal enzyme have been established with respect to cofactor requirements, kinetics, pH, addition of inhibitors, addition of glycerol phosphatides, and sterol substrate specificity. The 14-reductase is readily solubilized with a mixture of octylglucoside and taurodeoxycholic acid. The solubilized enzyme has been enriched by precipitation with polyethylene glycol and chromatography on DEAE-Sephacel and hydroxylapatite columns. The resulting partially purified enzyme has been obtained free of other microsomal enzymes of cholesterol biosynthesis: 4-methyl sterol oxidase, Δ5,7-sterol 7-reductase, Δ8,24-sterol 24-reductase, 3-ketosteroid reductase, and steroid 8 → 7-ene isomerase, plus microsomal cytochrome P-450, cytochrome P-450 reductase, cytochrome b5 reductase, and cytochrome b5. The partially purified enzyme is stimulated by addition of phospholipids. All of the properties exhibited by partially purified 14-reductase are consistent with the suggestion that the solubilized and enriched enzyme catalyzes the microsomal reduction of the 14-double bond of the sterol-conjugated dienes. However, presence of the enzyme does not prove that the sterol-conjugated dienes are obligatory precursors of cholesterol.",
author = "Paik, {Y. K.} and Trzaskos, {J. M.} and A. Shafiee and Gaylor, {J. L.}",
year = "1984",
month = "12",
day = "1",
language = "English",
volume = "259",
pages = "13413--13423",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "21",

}

Microsomal enzymes of cholesterol biosynthesis from lanosterol. Characterization, solubilization, and partial purification of NADPH-dependent Δ8,14-steroid 14-reductase. / Paik, Y. K.; Trzaskos, J. M.; Shafiee, A.; Gaylor, J. L.

In: Journal of Biological Chemistry, Vol. 259, No. 21, 01.12.1984, p. 13413-13423.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Microsomal enzymes of cholesterol biosynthesis from lanosterol. Characterization, solubilization, and partial purification of NADPH-dependent Δ8,14-steroid 14-reductase

AU - Paik, Y. K.

AU - Trzaskos, J. M.

AU - Shafiee, A.

AU - Gaylor, J. L.

PY - 1984/12/1

Y1 - 1984/12/1

N2 - The membrane-bound enzyme of microsomes that catalyzes NADPH-dependent reduction of the 14-double bond of conjugated Δ8,14- and Δ7,14-sterols has been studied both as collected in microsomes from broken cell preparations of rat liver and after solubilization. Optimal incubation conditions for assay of the membrane-bound enzyme have been determined, and properties of the microsomal enzyme have been established with respect to cofactor requirements, kinetics, pH, addition of inhibitors, addition of glycerol phosphatides, and sterol substrate specificity. The 14-reductase is readily solubilized with a mixture of octylglucoside and taurodeoxycholic acid. The solubilized enzyme has been enriched by precipitation with polyethylene glycol and chromatography on DEAE-Sephacel and hydroxylapatite columns. The resulting partially purified enzyme has been obtained free of other microsomal enzymes of cholesterol biosynthesis: 4-methyl sterol oxidase, Δ5,7-sterol 7-reductase, Δ8,24-sterol 24-reductase, 3-ketosteroid reductase, and steroid 8 → 7-ene isomerase, plus microsomal cytochrome P-450, cytochrome P-450 reductase, cytochrome b5 reductase, and cytochrome b5. The partially purified enzyme is stimulated by addition of phospholipids. All of the properties exhibited by partially purified 14-reductase are consistent with the suggestion that the solubilized and enriched enzyme catalyzes the microsomal reduction of the 14-double bond of the sterol-conjugated dienes. However, presence of the enzyme does not prove that the sterol-conjugated dienes are obligatory precursors of cholesterol.

AB - The membrane-bound enzyme of microsomes that catalyzes NADPH-dependent reduction of the 14-double bond of conjugated Δ8,14- and Δ7,14-sterols has been studied both as collected in microsomes from broken cell preparations of rat liver and after solubilization. Optimal incubation conditions for assay of the membrane-bound enzyme have been determined, and properties of the microsomal enzyme have been established with respect to cofactor requirements, kinetics, pH, addition of inhibitors, addition of glycerol phosphatides, and sterol substrate specificity. The 14-reductase is readily solubilized with a mixture of octylglucoside and taurodeoxycholic acid. The solubilized enzyme has been enriched by precipitation with polyethylene glycol and chromatography on DEAE-Sephacel and hydroxylapatite columns. The resulting partially purified enzyme has been obtained free of other microsomal enzymes of cholesterol biosynthesis: 4-methyl sterol oxidase, Δ5,7-sterol 7-reductase, Δ8,24-sterol 24-reductase, 3-ketosteroid reductase, and steroid 8 → 7-ene isomerase, plus microsomal cytochrome P-450, cytochrome P-450 reductase, cytochrome b5 reductase, and cytochrome b5. The partially purified enzyme is stimulated by addition of phospholipids. All of the properties exhibited by partially purified 14-reductase are consistent with the suggestion that the solubilized and enriched enzyme catalyzes the microsomal reduction of the 14-double bond of the sterol-conjugated dienes. However, presence of the enzyme does not prove that the sterol-conjugated dienes are obligatory precursors of cholesterol.

UR - http://www.scopus.com/inward/record.url?scp=0021688784&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021688784&partnerID=8YFLogxK

M3 - Article

C2 - 6444198

AN - SCOPUS:0021688784

VL - 259

SP - 13413

EP - 13423

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 21

ER -