钩端螺旋体中的糖合成。II. 乙醛酸循环酶的存在。
Sugar synthesis in Leptospira. II. Presence of glyoxylate cycle enzymes.
作者信息
Yanagihara Y, Kobayashi S, Mifuchi I
出版信息
Microbiol Immunol. 1984;28(5):529-34. doi: 10.1111/j.1348-0421.1984.tb00705.x.
The presence and some properties of the key enzymes of the glyoxylate cycle, isocitrate lyase (threo-Ds-isocitrate glyoxylate-lyase, EC 4.1.3.1) and malate synthase (L-malate glyoxylate-lyase (CoA-acetylating) EC 4.1.3.2), were investigated in Leptospira biflexa. Isocitrate lyase activity was found for the first time in the organism. The enzyme was induced by ethanol but not by acetate. The optimum pH was 6.8. The activity was inhibited by phosphoenolpyruvate, a specific inhibitor of isocitrate lyase. The optimum pH of malate synthase of L. biflexa was about 8.5. The Km value for glyoxylate was 3.0 X 10(-3) M and the activity was inhibited by glycolate, the inhibitor. The results strongly suggested the presence of a glyoxylate cycle in Leptospira. The possibility that the glyoxylate cycle plays an essential role in the synthesis of sugars, amino acids and other cellular components as an anaplerotic pathway of the tricarboxylic acid cycle in Leptospira was discussed.
在双曲钩端螺旋体中研究了乙醛酸循环关键酶异柠檬酸裂解酶（苏糖-Ds-异柠檬酸乙醛酸裂解酶，EC 4.1.3.1）和苹果酸合酶（L-苹果酸乙醛酸裂解酶（辅酶A乙酰化），EC 4.1.3.2）的存在及一些特性。首次在该生物体中发现了异柠檬酸裂解酶活性。该酶由乙醇诱导而非乙酸诱导。最适pH为6.8。其活性受到异柠檬酸裂解酶的特异性抑制剂磷酸烯醇丙酮酸的抑制。双曲钩端螺旋体苹果酸合酶的最适pH约为8.5。乙醛酸的Km值为3.0×10⁻³ M，其活性受到抑制剂乙醇酸的抑制。结果有力地表明双曲钩端螺旋体中存在乙醛酸循环。讨论了乙醛酸循环作为双曲钩端螺旋体三羧酸循环的回补途径在糖类、氨基酸和其他细胞成分合成中发挥重要作用的可能性。
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