PROPERTIES OF MEMBRANE-BOUND AND SOLUBILIZED FORMS OF ALKALINE-PHOSPHATASE FROM HUMAN-LIVER
PROPERTIES OF MEMBRANE-BOUND AND SOLUBILIZED FORMS OF ALKALINE-PHOSPHATASE FROM HUMAN-LIVER
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DOI：
10.1016/0304-4165(85)90034-0
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发表时间：
1985-01-01
期刊：
影响因子：
--
通讯作者：
STINSON, RA
中科院分区：
文献类型：
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作者：
CHAKRABARTTY, A;STINSON, RA
为了确定人肝脏中碱性磷酸酶的性质是否会因从其天然环境中释放酶而改变，对膜结合和纯化形式以及通过应用磷脂酰肌醇特异性磷脂酶 C 释放的酶进行了研究。结合酶对 8 种底物和竞争性抑制剂苯膦酸具有最低的亲和力。结合酶的无机磷酸盐的 Ki 值低于其他形式，而非竞争性抑制剂的值与所有 3 种酶相同。苯乙二醛与精氨酸的必需残基以与结合酶和纯化酶类似的速率反应，而必需阳离子在结合和释放形式中更容易去除和替换。结合酶的阿伦尼乌斯图显示有 2 个断裂，其活化能高于第二个断裂，与纯化酶的活化能相似。当膜受到丁醇干扰并在低于 30°C 的温度进行测定时，结合酶的活性增加。 C.这些实验表明，尽管碱性磷酸酶与质膜的结合对于催化功能不是必需的，但是膜中酶的性质与可溶形式的酶的性质不同。
To determine whether the properties of alkaline phosphatase in human liver are altered by releasing the enzyme from its native environment, the membrane-bound and purified forms, and the enzyme released by applying phosphatidylinositol-specific phospholipase C were studied. The bound enzyme had the lowest affinities for 8 substrates and the competitive inhibitor phenylphosphonate. The Ki for inorganic phosphate was lower with the bound enzyme than with the other forms, whereas the values for uncompetitive inhibitors were the same with all 3. Phenylglyoxal reacted with essential residues of arginine at similar rates with the bound and purified enzymes, whereas essential cations were more readily removed and replaced in the bound and released forms. Arrhenius plots of the bound enzyme revealed 2 breaks, with activation energy above the 2nd break similar to that of the purified enzyme. Activity of the bound enzyme increased when the membrane was perturbed by butanol and assayed below 30.degree. C. These experiments demonstrate that, even though binding of alkaline phosphatase to the plasma membrane is not essential for catalytic function, the properties of the enzyme in the membrane are different from those of the soluble form.