Identification in Tetrahymena pyriformis of 3-hydroxy-3-methyl glutaryl coenzyme a lyase: its purification and properties

Abstract

1. 1. The major HMG-CoA utilizing enzyme activity in T. pyriformis has been determined to be HMG-CoA lyase. 2. 2. The enzyme was purified 32-fold to a specific activity of 431 units/mg from a mitochondrial fraction. 3. 3. Sephacryl S-200 chromatography gave an estimated molecular weight of 50,000 daltons for the HMG-CoA lyase. SDS gel electrophoresis revealed two bands stained by Coomassie Blue—a major band of 50,000 daltons and a minor band of 25,000 daltons. The latter is believed to be an impurity in the preparation. 4. 4. The enzyme has a pH optimum of 9.0, is stimulated slightly by sulfhydryl reagents, and requires a divalent cation for maximum activity. 5. 5. The K M for HMG-CoA is 15 μM.