Purification of 3-hydroxy-3-methylglutaryl coenzyme A reductase from human liver.

The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase from human liver was purified to homogeneity. Electrophoresis of the purified human enzyme on non-denaturing gels revealed a single protein-staining band that co-migrated with reductase activity and could be selectively removed by treatment with cross-reacting antibody prepared to the purified reductase from rat liver. On SDS polyacrylamide gel electrophoresis, the purified reductase showed only one protein-staining band corresponding to a molecular weight of approximately 52,000. Based on the sedimentation rate during sucrose density gradient centrifugation, most of the enzyme from crude solubilized preparations had an apparent molecular weight of approximately 104,000. The human reductase, like the rat liver enzyme, was dimeric and composed of subunits of approximately 50,000 molecular weight.