Liu F, Fromm H J
Department of Biochemistry and Biophysics, Iowa State University of Science and Technology, Ames 50011.
Arch Biochem Biophys. 1988 Feb 1;260(2):609-15. doi: 10.1016/0003-9861(88)90488-2.
Fructose-1,6-bisphosphatase from bovine brain tissue has been purified to near homogeneity. This enzyme is similar to other mammalian fructose-1,6-bisphosphatases in many respects, and its properties are distinctly different from those reported for the enzyme from rat brain [A. L. Majumder and F. Eisenberg (1977) Proc. Natl. Acad. Sci. USA 74, 3222-3225; S. Chattoraj and A. L. Majumder (1986) Biochem. Biophys. Res. Commun. 139, 571-580]. The bovine enzyme (sp act 4, pH ratio (7.5/9.6) = 3.6) has a pH optimum of 7.5. The Km is 2 microM. Divalent metal ion is required for activity, and Vmax is obtained at either 4 mM Mg2+ or 0.3 mM Mn2+. Fructose 2,6-bisphosphate is a competitive inhibitor (Ki = 0.07 microM), and AMP a noncompetitive inhibitor (kis = 24 microM, Kii = 10 microM) of bovine brain fructose-1,6-bisphosphatase. The enzyme activity is enhanced by small amounts of EDTA relative to metal, and AMP inhibits fructose-1,6-bisphosphatase in either the presence or absence of the metal chelator; however, AMP is more effective in the absence of EDTA.
牛脑组织中的果糖-1,6-二磷酸酶已被纯化至接近均一。该酶在许多方面与其他哺乳动物的果糖-1,6-二磷酸酶相似，但其性质与报道的大鼠脑该酶明显不同[A. L. 马宗德和F. 艾森伯格（1977年）《美国国家科学院院刊》74, 3222 - 3225；S. 查托拉杰和A. L. 马宗德（1986年）《生物化学与生物物理学研究通讯》139, 571 - 580]。牛酶（比活性4，pH比（7.5/9.6） = 3.6）的最适pH为7.5。Km为2微摩尔。活性需要二价金属离子，在4毫摩尔Mg2+或0.3毫摩尔Mn2+时可获得最大反应速度（Vmax）。果糖2,6-二磷酸是牛脑果糖-1,6-二磷酸酶的竞争性抑制剂（Ki = 0.07微摩尔），AMP是非竞争性抑制剂（抑制常数分别为24微摩尔和10微摩尔）。相对于金属，少量的EDTA可增强酶活性，并且无论有无金属螯合剂，AMP均抑制果糖-1,6-二磷酸酶；然而，在没有EDTA时AMP更有效。
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