Letter: On the coupling of adenosine triphosphate hydrolysis to a simple inorganic redox system: VO2+ plus H2O2.
Letter: On the coupling of adenosine triphosphate hydrolysis to a simple inorganic redox system: VO2+ plus H2O2.
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信件：三磷酸腺苷水解与简单无机氧化还原系统：VO2 加 H2O2 的偶联。
DOI：
10.1021/ja00831a039
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发表时间：
1974
影响因子：
15
通讯作者：
G. Haight
中科院分区：
文献类型：
--
作者：
G. Woltermann;R. A. Scott;G. Haight
酶催化的三磷酸腺苷（ATP）水解为二磷酸腺苷（ADP）和无机磷酸(P)，为许多生物过程提供了主要的能量来源。许多工作者已经对ATP的非酶水解进行了研究1-4，以了解更多酶系统催化的机制。在许多生物学情况下，ATP水解似乎与某些电子转移反应同时发生。本研究主要是在非酶体系中研究简单的无机氧化还原反应（H2O2氧化V02+）对ATP水解的催化作用，以验证由多磷酸盐介导的氧化还原反应使磷稳定为取代的理论。通过监测ATP的水解速率，使用由Baginski等人改进的钼蓝法测定磷酸盐，5用于核苷磷酸的存在。标准正磷酸盐溶液（添加和不添加ATP）与A700（磷钼蓝配合物在700 nm处的吸光度）呈线性关系，P′斜率为（1.55±1.07）× 104/-1。所有运行均使用试剂级VOSO4、Na2H2ATP·4H2O （Sigma Chemical Co.）和H2O2溶液。在所有运行中，磷酸盐将溶液缓冲至pH~ 2.5。在这项初步研究中只监测了pj的形成，但正如下面提到的，任何形成的p2o74都可能被水解成P，这一过程类似于ATP水解。我们在表1中总结的初步发现显示了ATP水解的比较速率，揭示了VO2“1”的适度增强和与H2O2氧化VO24“的偶联显著增强。hulet2给出的ATP非催化水解的一级速率常数为~ 8 X 10-8秒-1 （pH值为4,25）。Hofstetter等人也观察到，在水杨基磷酸的情况下，仅VO24 ‘ ’就能增强磷酸酯的水解。6
The enzyme-catalyzed hydrolysis of adenosine triphos-phate (ATP) to adenosine diphosphate (ADP) and inorgan-ic phosphate (P¡) provides the main source of energy for many biological processes. Nonenzymatic hydrolysis of ATP has been investigated by many workers1-4 in an effort to learn more about the mechanism of catalysis by enzy-matic systems. In many biological cases, it appears that ATP hydrolysis occurs simultaneously with some electron transfer reaction. The present work is largely an effort to study catalysis of ATP hydrolysis by a simple inorganic redox reaction (H2O2 oxidation of V02+) in a nonenzyma-tic system to test a theory that redox reactions mediated by polyphosphates labilize phosphorus to substitution. Hydrolysis rates of ATP were followed by monitoring the amount of P¡ produced, using the molybdenum blue method for phosphate determination as modified by Baginski, et al., 5 for use in thepresence of nucleoside phosphates. Standard orthophosphate solutions (with and without added ATP) showed a linear dependence of A700 (absorbance of phosphomolybdenum blue complex at 700 nm) with [P¡] giving a slope of (1.55±1.07) X 104/-1. All runs were made using solutions of reagent grade VOSO4, Na2H2ATP· 4H2O (Sigma Chemical Co.), and H2O2. Phosphate present buffered the solution to pH~ 2.5 in all runs. Only Pjformation was monitored in this prelimi-nary study, but as mentioned below any P2O74-formed would probably be hydrolyzed to P¡ by a process similar to that for ATP hydrolysis.Our initial findings summarized in Table I show comparative rates of hydrolysis of ATP, revealing moderate en-hancement by VO2" 1" and dramatic enhancement by cou-pling with H2O2 oxidation of VO24". Hulett2 gives a value of~ 8 X 10-8 sec-1 for the first-order rate constant of the un-catalyzed hydrolysis of ATP (at pH 4, 25). Enhancement of phosphate ester hydrolysis by VO24" alone has also been observed by Hofstetter, et al., in the case of salicylphos-phate. 6