Enzymic Cleavage of Malate to Glyoxylate and Acetyl-Coenzyme A

Abstract

The cells of Rhodopseudomonas spheroides were sonicated in 0.02 [image] phosphate buffer (pH 7.4), centrifuged (75,000 x g), the supernatant treated with protamine at pH 7.0, the filtrate fractionated by (NH4)2 SO4 between 40 and 65% saturation, absorbed on Ca3 (PO4)2 gel at pH 6.8, eluted with 0.02 [image] K2HPO4 and refractionated by (NH4)2SO4 between 50 and 60% saturation. The preparation contained malate cleavage enzyme, purified about 4 fold, and was free of succinyl-CoA synthease or succinyl-CoA - malate transferase. It consisted of malyl-CoA synthease that was activated by adenosine-trlphosphate (ATP) and Mg2+ and malyl-CoA lyase. By the successive action of these 2 enzymes, malate was stoichiometrically degraded to glyoxylate and acetyl-CoA, accompanied by the formation of adenosine-diphosphate (ADP) and inorganic P (IP). The reverse reaction was also catalyzed by the enzyme preparation, but the adenylate-pyrophosphate mixture could not replace ADP and iP.