ATP binding at noncatalytic sites of soluble chloroplast F1-ATPase is required for expression of the enzyme activity.
ATP binding at noncatalytic sites of soluble chloroplast F1-ATPase is required for expression of the enzyme activity.
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发表时间：
1990-11
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通讯作者：
Y. Milgrom;L. Ehler;P. Boyer
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作者：
Y. Milgrom;L. Ehler;P. Boyer
如果ATP未结合在非催化位点，则来自叶绿体（CF 1）的F1-ATP酶缺乏ATP水解的催化能力。在ADP存在下热激活的CF 1，在非催化位点具有少于一个ADP且没有ATP，在暴露于5-20 μ M ATP后显示出ATP水解的开始明显滞后。活性的发作与ATP在三个非催化位点中的最后两个的结合密切相关。在相对低或高的游离Mg 2+浓度下，有或没有碳酸氢根作为活化阴离子，以及当ATP在非催化位点的结合被硫酸盐减慢3-4倍时，显示出活性对非催化位点处ATP存在的依赖性。被二硫苏糖醇激活的潜在CF 1也需要ATP酶活性的非催化位点处的ATP。其他F1-ATP酶和ATP酶的类似要求似乎是合理的。
The F1-ATPase from chloroplasts (CF1) lacks catalytic capacity for ATP hydrolysis if ATP is not bound at noncatalytic sites. CF1 heat activated in the presence of ADP, with less than one ADP and no ATP at non-catalytic sites, shows a pronounced lag in the onset of ATP hydrolysis after exposure to 5-20 microM ATP. The onset of activity correlates well with the binding of ATP at the last two of the three noncatalytic sites. The dependence of activity on the presence of ATP at non-catalytic sites is shown at relatively low or high free Mg2+ concentrations, with or without bicarbonate as an activating anion, and when the binding of ATP at noncatalytic sites is slowed 3-4-fold by sulfate. The latent CF1 activated by dithiothreitol also requires ATP at noncatalytic sites for ATPase activity. A similar requirement by other F1-ATPases and by ATP synthases seems plausible.