来自大豆根瘤植物胞质部分的己糖激酶。
Hexose kinases from the plant cytosolic fraction of soybean nodules.
作者信息
Copeland L, Morell M
机构信息
Department of Agricultural Chemistry, University of Sydney, New South Wales 2006, Australia.
出版信息
Plant Physiol. 1985 Sep;79(1):114-7. doi: 10.1104/pp.79.1.114.
The enzymes responsible for the phosphorylation of hexoses in the plant cytosolic fraction of soybean (Glycine max L. Merr cv Williams) nodules have been studied and a hexokinase (ATP:d-hexose 6-phosphotransferase EC 2.7.1.1) and fructokinase (ATP:d-fructose 6-phosphotransferase EC 2.7.1.4) shown to be involved. The plant cytosolic hexokinase had optimum activity from pH 8.2 to 8.9 and the enzyme displayed typical Michaelis-Menten kinetics. Hexokinase had a higher affinity for glucose (K(m) 0.075 millimolar) than fructose (K(m) 2.5 millimolar) and is likely to phosphorylate mainly glucose in vivo. The plant cytosolic fructokinase had a pH optimum of 8.2 and required K(+) ions for maximum activity. The enzyme was specific for fructose (apparent K(m) 0.077 millimolar) but concentrations of fructose greater than 0.4 millimolar were inhibitory. The native molecular weight of fructokinase was 84,000 +/- 5,000. The roles of these enzymes in the metabolism of glucose and fructose in the host cytoplasm of soybean nodules are discussed.
对大豆（Glycine max L. Merr cv Williams）根瘤植物胞质部分中负责己糖磷酸化的酶进行了研究，结果表明一种己糖激酶（ATP：D-己糖6-磷酸转移酶，EC 2.7.1.1）和果糖激酶（ATP：D-果糖6-磷酸转移酶，EC 2.7.1.4）参与其中。植物胞质己糖激酶在pH 8.2至8.9时具有最佳活性，且该酶表现出典型的米氏动力学。己糖激酶对葡萄糖（K(m) 0.075毫摩尔）的亲和力高于果糖（K(m) 2.5毫摩尔），在体内可能主要使葡萄糖磷酸化。植物胞质果糖激酶的最适pH为8.2，且需要K(+)离子才能达到最大活性。该酶对果糖具有特异性（表观K(m) 0.077毫摩尔），但果糖浓度大于0.4毫摩尔时具有抑制作用。果糖激酶的天然分子量为84,000 +/- 5,000。讨论了这些酶在大豆根瘤宿主细胞质中葡萄糖和果糖代谢中的作用。
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