Acetoacetate Decarboxylase and a Peptide with Similar Activity Produced by Bacillus polymyxa A-57(Biological Chemistry)

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Acetoacetate decarboxylase is a valuable tool for clinical analysis of ketone bodies in human plasma. After screening many microorganisms, we found Bacillus polymyxa A-57 to be a new enzyme source with a good yield of acetoacetate decarboxylase. After purifying the intracellular enzyme by three-stage column chromatography, we identified it as a single protein by SDS-polyacrylamide gel electrophoresis. The enzyme had a molecular weight of approximately 280,000 and consisted of 10 (±2) identical subunits. It had an optimum pH of 5.9 and was stable up to about 60℃ for 30 min. The apparent Km and V_<max> values for lithium acetoacetate were 0.94 mM and 296 μmol/min/mg, respectively. In addition, the decarboxylase activity was found in the broth. After purification, we found that it was due to an active peptide which we named A-57-9, which we identified as the antibiotic polymyxin M_1. However, the V_<max> value (0.25 μmol/min/mg) of the peptide was very much lower and the Km value (400 mM) was higher than those of real acetoacetate decarboxylase.
社団法人日本農芸化学会の論文
1986-10-23