INFLUENCE OF A NATURALLY OCCURRING COMPETING ENZYMIC ACTIVITY ON STUDIES OF 3-HYDROXY-3-METHYLGLUTARYL COENZYME A REDUCTASE-ACTIVITY

被引：23

作者：

NESS, GC

MOFFLER, MH

机构：

[1] Department of Biochemistry, College of Medicine, University of South Florida, Tampa

来源：

BIOCHIMICA ET BIOPHYSICA ACTA | 1979年 / 572卷 / 02期

关键词：

Competing enzyme; Hydroxymethylglutaryl-CoA reductase;

D O I：

10.1016/0005-2760(79)90049-3

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

An enzymic activity which competes with 3-hydroxy-3-methylglutaryl coenzyme A reductase for d-hydroxymethylglutaryl CoA has been found in isolated rat liver microsomes and in microsomal extracts. The presence of this activity in enzyme preparations causes a decrease in the rate of mevalonate formation leading to an underestimation of reductaae activity and an overestimation of the apparent Km of the reductase. The product formed by this competing enzymic activity behaves similarly to, but not identically with, mevalonolactone when chromatographed on Bio-Rad AG l-x8 formate, which is used in many reductase assay procedures to separate mevalonolactone from hydroxymethylglutaryl CoA. Removal of this competing enzymic activity from reductase preparations can be accomplished by gel filtration using Bio-Gel A 1.5m, by washing the microsomes or by incubating the microsomal extract at 37°C. Using enzyme preparations free of this competing enzymic activity, the apparent Km values of the reductase for d-hydroxymethylglutaryl CoA and NADPH were found to be 1.3 and 26 μM respectively. © 1979.

引用

页码：333 / 344

页数：12

共 42 条

[1] SOLUBILIZATION OF 3-HYDROXY-3-METHYLGLUTARYL COENZYME-A REDUCTASE FROM LYOPHILIZED RAT-LIVER MICROSOMES - LACK OF EVIDENCE FOR COLD LABILITY IN THIS SOLUBLE ENZYME PREPARATION [J].