Acetoacetate Decarboxylase and a Peptide with Similar Activity Produced by Bacillus polymyxa A-57 |
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| Authors: | Yukio Kimura Noriko Yasuda Hiroko Tanigaki-Nagae Toshikatsu Nakabayashi Hisami Matsunaga Masako Kimura |
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| Institution: | 1. Faculty of Pharmaceutical Sciences, Mukogawa Women’s University, 4–16, Edagawa-cho, Nishinomiya 663, Japan;2. Department of Clinical Pathology and Clinical Laboratory, Hyogo College of Medicine, 1–1, Mukogawa-cho, Nishinomiya 663, Japan |
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| Abstract: | 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°C for 30min. The apparent Km and Vmax values for lithium acetoacetate were 0.94 mm and 296 μmiol/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 M1. However, the Vmax 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. |
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