Loewus M W, Bedgar D L, Loewus F A
J Biol Chem. 1984 Jun 25;259(12):7644-7.
1L-Inositol 1-phosphate synthase (EC 5.5.1.4) devoid of bound NAD+ was isolated from mature pollen of Lilium longiflorum ( Easter lily ). The enzyme has a molecular weight of 157,000 +/- 15,000 and a subunit weight of 61,000 +/- 5,000. Kinetic studies of the uninhibited reaction and of inhibition by 2-deoxy-D-glucose 6-phosphate and NADH show the reaction to be ordered sequential with NAD+ adding first. The Michaelis constants for NAD+ and D-glucose 6-phosphate are 2.4 and 65 microM, respectively. The Ki for 2-deoxy-D-glucose 6-phosphate was 8.7 and 2.0 microM, respectively, when D-glucose 6-phosphate or NAD+ was varied. The Ki for NADH and variable NAD+ was 4.7 microM and, for NADH and variable D-glucose 6-phosphate, 3.9 microM.
从麝香百合（复活节百合）的成熟花粉中分离出无结合态NAD⁺的1L-肌醇1-磷酸合酶（EC 5.5.1.4）。该酶的分子量为157,000±15,000，亚基分子量为61,000±5,000。对无抑制反应以及2-脱氧-D-葡萄糖6-磷酸和NADH抑制作用的动力学研究表明，该反应为有序序列反应，首先添加NAD⁺。NAD⁺和D-葡萄糖6-磷酸的米氏常数分别为2.4和65微摩尔。当D-葡萄糖6-磷酸或NAD⁺变化时，2-脱氧-D-葡萄糖6-磷酸的抑制常数Ki分别为8.7和2.0微摩尔。NADH与可变NAD⁺的抑制常数Ki为4.7微摩尔，NADH与可变D-葡萄糖6-磷酸的抑制常数Ki为3.9微摩尔。
