Blázquez M A, Lagunas R, Gancedo C, Gancedo J M
Instituto de Investigaciones Biomédicas, CSIC, Madrid, Spain.
FEBS Lett. 1993 Aug 23;329(1-2):51-4. doi: 10.1016/0014-5793(93)80191-v.
Trehalose-6-phosphate (P) competitively inhibited the hexokinases from Saccharomyces cerevisiae. The strongest inhibition was observed upon hexokinase II, with a Ki of 40 microM, while in the case of hexokinase I the Ki was 200 microM. Glucokinase was not inhibited by trehalose-6-P up to 5 mM. This inhibition appears to have physiological significance, since the intracellular levels of trehalose-6-P were about 0.2 mM. Hexokinases from other organisms were also inhibited, while glucokinases were unaffected. The hexokinase from the yeast, Yarrowia lipolytica, was particularly sensitive to the inhibition by trehalose-6-P: when assayed with 2 mM fructose an apparent Ki of 5 microM was calculated. Two S. cerevisiae mutants with abnormal levels of trehalose-6-P exhibited defects in glucose metabolism. It is concluded that trehalose-6-P plays an important role in the regulation of the first steps of yeast glycolysis, mainly through the inhibition of hexokinase II.
6-磷酸海藻糖竞争性抑制酿酒酵母中的己糖激酶。己糖激酶II受到的抑制作用最强，其抑制常数（Ki）为40微摩尔，而己糖激酶I的Ki为200微摩尔。在5毫摩尔浓度以下，葡萄糖激酶不受6-磷酸海藻糖的抑制。这种抑制作用似乎具有生理意义，因为细胞内6-磷酸海藻糖的水平约为0.2毫摩尔。来自其他生物的己糖激酶也受到抑制，而葡萄糖激酶则不受影响。解脂耶氏酵母的己糖激酶对6-磷酸海藻糖的抑制作用特别敏感：在用2毫摩尔果糖进行测定时，计算得出的表观Ki为5微摩尔。两个6-磷酸海藻糖水平异常的酿酒酵母突变体在葡萄糖代谢方面表现出缺陷。得出的结论是，6-磷酸海藻糖在酵母糖酵解第一步的调节中起重要作用，主要是通过抑制己糖激酶II来实现的。
