Toyoda Y, Miwa I, Ogiso S, Okuda J
Department of Clinical Biochemistry, Faculty of Pharmacy, Meijo University, Nagoya, Japan.
Biochem Mol Biol Int. 1993 Mar;29(3):587-94.
Chromatography of crude rat muscle extracts on CM-cellulose resulted in separation of glucose-6-phosphate isomerase (GPI) into two active peaks (designated types I and II in order of elution). Incubation of type I and type II at pH 6.0, 7.0, or 8.0 in the presence and absence of KCI revealed that one type of GPI is converted to the other type under certain conditions and that the two types are interconvertible by changing the incubation conditions. The two types were similar in molecular weight, kinetic property, and optimum pH. A remarkable difference was observed in pH-activity profile: the activity of type I, but not type II, was detectable at pH 6-7. The present results suggest that rat muscle has two types of GPI which are interconvertible and that the two types may be conformational variants of the same enzyme. It is conceivable that the interconversion between the two types is related to the regulation of glycolysis at lower intracellular pHs.
用CM - 纤维素对大鼠肌肉粗提物进行色谱分析，结果显示葡萄糖 - 6 - 磷酸异构酶（GPI）被分离为两个活性峰（按洗脱顺序分别命名为I型和II型）。在有和没有KCl存在的情况下，将I型和II型在pH 6.0、7.0或8.0条件下孵育，结果表明，一种类型的GPI在某些条件下会转化为另一种类型，并且通过改变孵育条件，这两种类型可以相互转化。这两种类型在分子量、动力学性质和最适pH方面相似。在pH - 活性图谱中观察到一个显著差异：在pH 6 - 7时可检测到I型的活性，但II型没有。目前的结果表明，大鼠肌肉中有两种可相互转化的GPI，并且这两种类型可能是同一种酶的构象变体。可以设想，这两种类型之间的相互转化与细胞内较低pH值时糖酵解的调节有关。
