Gee N S, Reid G G, Jackson R G, Barnaby R J, Ragan C I
Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, U.K.
Biochem J. 1988 Aug 1;253(3):777-82. doi: 10.1042/bj2530777.
Inositol-1,4-bisphosphatase has been purified 13,000-fold from bovine brain supernatant. The enzyme is monomeric, with an apparent subunit Mr of 40,000. Maximal hydrolytic rates were observed in Tris buffer, pH 7.8, in the presence of 9 mM-Mg2+. The enzyme acted as a 1-phosphatase, hydrolysing both inositol 1,4-bisphosphate [Ins(1,4)P2] (Km 0.04 mM) and inositol 1,3,4-trisphosphate [Ins(1,3,4)P3] (Km 0.5 mM) to inositol 4-phosphate and inositol 3,4-bisphosphate respectively. Li+ inhibited the hydrolysis of both substrates in an uncompetitive manner, with apparent Ki values of 9.63 mM and 0.46 mM for Ins(1,4)P2 and Ins(1,3,4)P3 respectively.
肌醇-1,4-二磷酸酶已从牛脑上清液中纯化了13000倍。该酶为单体，表观亚基分子量为40000。在pH 7.8的Tris缓冲液中，9 mM - Mg2+存在下观察到最大水解速率。该酶作为一种1-磷酸酶，将肌醇1,4-二磷酸[Ins(1,4)P2]（Km 0.04 mM）和肌醇1,3,4-三磷酸[Ins(1,3,4)P3]（Km 0.5 mM）分别水解为肌醇4-磷酸和肌醇3,4-二磷酸。Li+以非竞争性方式抑制两种底物的水解，对Ins(1,4)P2和Ins(1,3,4)P3的表观Ki值分别为9.63 mM和0.46 mM。
