3-Hydroxy-3-methylglutaryl coenzyme A lyase from Pseudomonas mevalonii.

HMG-CoA lyase, the putative second intracellular enzyme of mevalonate catabolism in Pseudomonas mevalonii (which we previously referred to as Pseudomonas sp. M (Gill et al. (1984) J. Bacteriol. 160, 294-298, Gill et al. (1985) J. Biol. Chem. 250, 9393-9398 and Sherban, M.S., Thesis, Purdue University), was purified 650-fold from cell extracts to a specific activity of 22 mumol acetyl-CoA formed per min per mg protein. This represents the first published report of the partial purification and characterization of an HMG-CoA lyase from a prokaryotic source. Cleavage of HMG-CoA produced acetyl-CoA and acetoacetate. Activity was optimal at pH 8.8 and was undetectable at or below pH 6.5. The estimated Km for S-HMG-CoA was 100 microM. Both a reduced thiol and Mg2+ or Mn2+ were required for activity. While Mn2+ was preferred at low concentrations, 1 mM or higher concentrations of either cation supported the same maximum velocity. An apparent native Mr of 40,400 +/- 3100 was estimated from gel filtration and sucrose density gradient ultracentrifugation data.