Babul J, Guixé V
Arch Biochem Biophys. 1983 Sep;225(2):944-9. doi: 10.1016/0003-9861(83)90109-1.
Escherichia coli fructose-1,6-bisphosphatase has been purified for the first time, using a clone containing an approximately 50-fold increased amount of the enzyme. The procedure includes chromatography in phosphocellulose followed by substrate elution and gel filtration. The enzyme has a subunit molecular weight of approximately 40,000 and in nondenaturing conditions is present in several aggregated forms in which the tetramer seems to predominate at low enzyme concentrations. Fructose bisphosphatase activity is specific for fructose 1,6-bisphosphate (Km of approximately 5 microM), shows inhibition by substrate above 0.05 mM, requires Mg2+ for catalysis, and has a maximum of activity around pH 7.5. The enzyme is susceptible to strong inhibition by AMP (50% inhibition around 15 microM). Phosphoenolpyruvate is a moderate inhibitor but was able to block the inhibition by AMP and may play an important role in the regulation of fructose bisphosphatase activity in vivo. Fructose 2,6-bisphosphate did not affect the rate of reaction.
利用含有约50倍酶量增加的克隆，首次纯化了大肠杆菌果糖-1,6-二磷酸酶。该方法包括磷酸纤维素柱层析，随后进行底物洗脱和凝胶过滤。该酶的亚基分子量约为40,000，在非变性条件下以几种聚集形式存在，其中四聚体在低酶浓度下似乎占主导地位。果糖二磷酸酶活性对果糖1,6-二磷酸具有特异性（Km约为5 microM），在底物浓度高于0.05 mM时表现出抑制作用，催化反应需要Mg2+，并且在pH 7.5左右具有最大活性。该酶对AMP的强烈抑制敏感（在约15 microM时50%抑制）。磷酸烯醇丙酮酸是一种中度抑制剂，但能够阻断AMP的抑制作用，并且可能在体内果糖二磷酸酶活性的调节中起重要作用。果糖2,6-二磷酸不影响反应速率。
