Journal of Lipid Research, Vol 17, 297-303, Copyright © 1976 by Lipid Research, Inc.
Improved methods for the study of hepatic HMG CoA reductase: one-step isolation of mevalonolactone and rapid preparation of endoplasmic reticulum
CD Goodwin and S Margolis
Two new methods are described for the study of hepatic 3-hydroxy-3-
methylglutaryl coenzyme A (HMG CoA) reductase. (1) Endoplasmic reticulum
was rapidly prepared by diluting a 10,000 g supernatant with buffer
containing 8 mM calcium chloride. The yield of protein and the specific
activity of HMG CoA reductase in the pellet subsequently obtained by low
speed centrifugation were nearly identical to those in the microsomal
pellet prepared by ultracentrifugation. This technique may be particularly
useful in studies of the rapid, in vitro modulation of the enzyme. (2)
Mevalonolactone was extracted into benzene from the HMG CoA reductase assay
mixture with an efficiency of 58%. There was less than 1% extraction of HMG
CoA, acetoacetate, or beta- hydroxybutyrate. The extracted mevalonolactone
was at least 98% pure as judged by thin-layer chromatography with four
different solvent systems. These improved methods should significantly aid
studies of the physiological importance of HMG CoA reductase.