pH-induced changes in Rhodospirillum rubrum cytochrome c2 and subsequent renaturation: an 15N NMR study.
pH-induced changes in Rhodospirillum rubrum cytochrome c2 and subsequent renaturation: an 15N NMR study.
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pH 诱导的红色红螺菌细胞色素 c2 变化及随后的复性：一项 15N NMR 研究。
DOI：
10.1073/pnas.85.9.2894
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发表时间：
1988
影响因子：
11.1
通讯作者：
Smith,GM
中科院分区：
文献类型：
--
作者：
Yu,LP;Smith,GM
利用15 N NMR研究了不同pH值下红杜鹃中15 N富集的铁细胞色素c2。的N-末端谷氨酸（335.4 ppm，在pH 5.1）的流动性和化学位移被发现依赖于pH值。它是最少的移动的之间的pH值8和9.0，这是解释在pH值依赖性的构象变化和形成的盐键和/或氢键。赖氨酸侧链的共振在低pH下以341.7 ppm为中心，并且随着pH向高场移动约8.4 ppm，pKa值为10.8。在它们的pKa值附近，NH质子的交换率最低。该蛋白在pH 4.9 - 10.0范围内非常稳定，但在pH 10.5-11时突然展开。通过NMR测量几个参数来验证变性。蛋白质的复性表明，折叠开始与血红素配位和建立一个疏水的核心，其次是定位的侧链和连接成核中心的肽骨架的重组。重新定位过程的时间尺度为几分钟到几小时，而在一些研究中报告的时间尺度为几秒。
The 15N-enriched ferrocytochrome c2 from Rhodospirillum rubrum was studied by 15N NMR at different solvent pH values. The mobility and chemical shift of the N-terminal glutamic acid (335.4 ppm at pH 5.1) were found to depend on pH. It was least mobile between pH 8 and 9.0, which is explained in terms of pH-dependent conformational changes and formation of salt linkages and/or hydrogen bonds. The resonances of the lysine side chains are centered around 341.7 ppm at low pH and move upfield with pH by about 8.4 ppm with pKa values of 10.8. The exchange rates of the epsilon NH protons are lowest near their pKa values. The protein is very stable in the pH range between 4.9 and 10.0 but unfolds abruptly at pH 10.5-11. Denaturation was verified by the measurement of several parameters by NMR. The renaturation of the protein demonstrates that the folding begins with reformation of heme coordination and establishment of a hydrophobic core, followed by positioning of side chains and peptide backbones linking the nucleation centers. The repositioning processes had time scales of minutes to hours in contrast to the reported values of seconds in some studies.