Characterization of conformational exchange of a histidine side chain:: Protonation, rotamerization, and tautomerization of His61 in plastocyanin from Anabaena variabilis
Characterization of conformational exchange of a histidine side chain:: Protonation, rotamerization, and tautomerization of His61 in plastocyanin from Anabaena variabilis
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DOI：
10.1021/ja801330h
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发表时间：
2008-07-02
影响因子：
15
通讯作者：
Kay, Lewis E.
中科院分区：
文献类型：
--
作者：
Hass, Mathias A. S.;Hansen, D. Flemming;Kay, Lewis E.
提出了一个描述可变鱼腥藻质体蓝蛋白His 61构象交换的模型.交换动力学的详细图片已获得使用溶液NMR弛豫测量，化学位移滴定，和由高分辨率的蛋白质晶体结构提供的结构信息。一个三站点模型的化学交换，涉及互变异构体和质子化形式的组氨酸侧链之间的相互转化的速率是快速的NMR化学位移时间尺度可以占所有的数据。一般来说，在快速交换的限制下，使用NMR不可能获得参与态的化学位移差异和布居的单独测量。然而，我们在这里表明，当上述数据相结合时，可以提取表征交换过程的所有参数的值，包括速率，种群和化学位移变化，并提供交叉验证，以确定其准确性。该方法一般适用于组氨酸侧链动力学的研究，它可以在许多蛋白质系统中发挥重要的功能作用。
A model describing conformational exchange of His 61 in plastocyanin from Anabaena variabilis is presented. A detailed picture of the exchange dynamics has been obtained using solution NMR relaxation measurements, chemical shift titrations, and structural information provided by a high-resolution crystal structure of the protein. A three-site model for chemical exchange that involves interconversion among the tautomeric and protonated forms of the histidine side chain with rates that are fast on the NMR chemical shift time scale can account for all of the data. In general, in the limit of fast exchange, it is not possible to obtain separate measures of chemical shift differences and populations of the participating states using NMR. However, we show here that when the data mentioned above are combined, it is possible to extract values of all of the parameters that characterize the exchange process, including rates, populations, and chemical shift changes, and to provide cross-validations that establish their accuracy. The methodology is generally applicable to the study of histidine side chain dynamics, which can play an important functional role in many protein systems.