Sakai K, Hasumi K, Endo A
Department of Applied Biological Science, Tokyo Noko University, Japan.
Eur J Biochem. 1990 Oct 5;193(1):195-202. doi: 10.1111/j.1432-1033.1990.tb19323.x.
The sesquiterpene lactone koningic acid (heptelidic acid) irreversibly inactivated glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde 3-phosphate: NAD+ oxidoreductase (phosphorylating)] (EC 1.2.1.12) (GAPDH) and thus inhibits glycolysis. The koningic-acid-producing strain of Trichoderma koningii M3947 was shown to contain the koningic-acid-resistant GAPDH isozyme (GAPDH I) under conditions of koningic acid production. In peptone-rich medium, however, no koningic acid production was observed, and the koningic-acid-sensitive GAPDH isozyme (GAPDH II), in addition to the resistant enzyme, was produced. Both enzymes were tetramer with a molecular mass of 152 kDa (4 x 38 kDa) and lost enzyme activity when two of the four cysteine residues reacted with koningic acid. The apparent Km values of GAPDH I and II for glyceraldehyde 3-phosphate were 0.54 mM and 0.33 mM, respectively. The former isozyme was inhibited 50% by 1 mM koningic acid but not affected at 0.1 mM, while the latter isozyme was inhibited 50% at 0.01 mM. The immunochemical properties and partial amino acid sequences suggested that the two isozymes have different molecular structures. These results suggest that GAPDH I is responsible for the glycolysis in T. koningii when koningic acid is produced.
倍半萜内酯 koningic 酸（庚酸）可不可逆地使甘油醛-3-磷酸脱氢酶[D-甘油醛 3-磷酸：NAD⁺氧化还原酶（磷酸化）]（EC 1.2.1.12）（GAPDH）失活，从而抑制糖酵解。研究表明，在产生 koningic 酸的条件下，康宁木霉 M3947 的产 koningic 酸菌株含有对 koningic 酸具有抗性的 GAPDH 同工酶（GAPDH I）。然而，在富含蛋白胨的培养基中，未观察到 koningic 酸的产生，除了抗性酶之外，还产生了对 koningic 酸敏感的 GAPDH 同工酶（GAPDH II）。这两种酶均为四聚体，分子量为 152 kDa（4×38 kDa），当四个半胱氨酸残基中的两个与 koningic 酸反应时，酶活性丧失。GAPDH I 和 II 对甘油醛 3-磷酸的表观 Km 值分别为 0.54 mM 和 0.33 mM。前一种同工酶在 1 mM koningic 酸作用下被抑制 50%，但在 0.1 mM 时不受影响，而后一种同工酶在 0.01 mM 时被抑制 50%。免疫化学性质和部分氨基酸序列表明这两种同工酶具有不同的分子结构。这些结果表明，当产生 koningic 酸时，GAPDH I 在康宁木霉的糖酵解过程中起作用。
