Tanaka K, Sakai H, Ohta T, Matsuzawa H
Department of Biotechnology, University of Tokyo, Japan.
Biosci Biotechnol Biochem. 1995 Aug;59(8):1536-42. doi: 10.1271/bbb.59.1536.
The genes for the pyruvate kinases of a psychrophile, Bacillus psychrophilus, and a mesophile, Bacillus licheniformis, have been cloned in Escherichia coli, and all their nucleotides were sequenced. The two bacterial enzymes each had an extra C-terminal sequence consisting of about 110 amino acid residues, which has been found in the B. stearothermophilus enzyme. Both enzymes were overexpressed in E. coli and the properties of the purified enzymes were compared to those of the B. stearothermophilus enzyme. Both enzymes were less stable than the B. stearothermophilus one. The B. psychrophilus enzyme was more stable than the B. licheniformis one. Similarly to the B. licheniformis and B. stearothermophilus pyruvate kinases, the B. psychrophilus enzyme was activated by AMP or ribose 5-phosphate, and inhibited by ATP or fructose 1,6-bisphosphate. Thus, these enzymes were very similar in the sigmoidal saturation curve for phosphoenolpyruvate and allosteric effectors, but their optimum temperatures and thermostabilities were very different.
嗜冷芽孢杆菌（Bacillus psychrophilus）和嗜温芽孢杆菌（Bacillus licheniformis）丙酮酸激酶的基因已在大肠杆菌中克隆，并对其所有核苷酸进行了测序。这两种细菌酶各自都有一个额外的C末端序列，由约110个氨基酸残基组成，该序列已在嗜热脂肪芽孢杆菌（B. stearothermophilus）的酶中发现。两种酶均在大肠杆菌中过表达，并将纯化酶的性质与嗜热脂肪芽孢杆菌的酶进行了比较。两种酶都比嗜热脂肪芽孢杆菌的酶稳定性差。嗜冷芽孢杆菌的酶比地衣芽孢杆菌的酶更稳定。与地衣芽孢杆菌和嗜热脂肪芽孢杆菌的丙酮酸激酶类似，嗜冷芽孢杆菌的酶被AMP或5-磷酸核糖激活，并被ATP或1,6-二磷酸果糖抑制。因此，这些酶在磷酸烯醇丙酮酸和变构效应剂的S形饱和曲线上非常相似，但它们的最适温度和热稳定性却非常不同。
