Preparation of a soluble 58kDa-3-hydroxy-3-methylglutaryl CoA reductase from liver microsomes and its inhibition by ethoxysilatrane, a hypocholesterolemic compound

Omkumar, RV and Mehta, PP and Kurup, Ramakrishna CK and Ramasarma, T (1992) Preparation of a soluble 58kDa-3-hydroxy-3-methylglutaryl CoA reductase from liver microsomes and its inhibition by ethoxysilatrane, a hypocholesterolemic compound. In: Molecular and Cellular Biochemistry, 110 (2). pp. 145-153.

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Abstract

On repeated thawing at room temperature of frozen preparations of heavy microsomes from rat livers, HMGCoA reductase activity was solubilized due to limited proteolysis. This soluble enzyme was partially purified by fractionation with ammonium sulfate and filtration on Sephacryl S-200 column. The active enzyme was coeluted with a major 92 kDa-protein and was identified as a 58kDa-protein after separation by SDS-PAGE and immunoblotting. Ethoxysilatrane, a hypocholesterolemic compound, which decreased the liver-microsomal activity of HMGCoA reductase on intra-peritonial treatment of animals, showed little effect on the enzyme activity with isolated microsomes or the 50kDa-soluble enzyme when added in the assay. But it was able to inhibit the activity of the soluble 58kDa-enzyme in a concentration-dependent, reversible manner. Cholesterol and an oxycholesterol were without effect whereas chlorophenoxyisobutyrate and ubiquinone showed small inhibition under these conditions. The extra region that links the active site domain (50kDa protein) to the membrane, present in the 58kDa-protein appears to be involved in mediating the inhibition by silatrane.

Item Type:	Journal Article
Publication:	Molecular and Cellular Biochemistry
Publisher:	Springer
Additional Information:	Copyright of this article belongs to Springer.
Keywords:	ethoxysilatrane;HMGCoA reductase;mevalonate biosynthesis.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	02 May 2011 04:46
Last Modified:	02 May 2011 04:46
URI:	http://eprints.iisc.ac.in/id/eprint/37347

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