Ionic strength dependence of cytochrome c structure and Trp-59 H/D exchange from ultraviolet resonance Raman spectroscopy.
Ionic strength dependence of cytochrome c structure and Trp-59 H/D exchange from ultraviolet resonance Raman spectroscopy.
复制标题
紫外共振拉曼光谱的细胞色素 c 结构和 Trp-59 H/D 交换的离子强度依赖性。
DOI：
10.1021/bi00438a022
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Spiro,TG
中科院分区：
文献类型：
--
作者：
Liu,GY;Grygon,CA;Spiro,TG
刘刚宇，克莉丝汀A. Grygon和托马斯G. Spiro** Department of Chemistry，Princeton University，Princeton，新泽西08544-1009接收于1988年12月1日;修订的Mandarin pt接收于1989年2月22日摘要：报道了Fe 11和Fe 111氧化态的细胞色素c（cyt c）在低（0.005 M）和高（0.9-1.5 M）离子强度下的紫外共振拉曼光谱。与200 nm激发的酰胺带强度保持不变，建立redoxstate和离子强度没有影响的螺旋内容。然而，对于Fe 111蛋白，酪氨酸830/850-cm-1双峰在I= 0.005 M时显示830-cm-1强度的损失，表明来自内部酪氨酸（可能是Tyr-48）的氢键的减弱或损失，所述内部酪氨酸与cyt c晶体中的血红素丙酸酯基团氢键结合。对于Fe 11和Fe 111形式的cyt c，色氨酸的激发谱在~ 229 nm处，但对于色氨酸水溶液，在~ 218 nm处。共振电子跃迁的~ 2200-cm-1红移归因于Trp-59残基被掩埋和H-键合。与该Trp环境一致，H-键敏感的877-cm-1 Trp带是强的和尖锐的，并且1357/1341-cm-1双峰对于Fe 11和Fe 111 cyt c都具有大的强度比，~ 1.5。当Trp吲哚质子被氘核取代时，877-cm-1-带频率移动到860 cm-1。该条带用于显示D20中的Trp H/D交换对于Fe 111比Fe 11 cyt c快得多。当在I=0.005下检查时，Fe 11和Fe 111在室温下的交换半衰期估计分别为~ 30和~ 5 h。然而，将离子强度增加至1.5 M，使Fe 111 cyt c的半衰期增加至约30 h，并使Fe 11 cyt c的半衰期增加至更大的值。蛋白质动力学的这种变化与Fe 111蛋白质的回转半径随着离子强度的降低而增加的最近证据一致（Trewhella et al.，1988年）。
Gang-yu Liu, Christine A. Grygon, and Thomas G. Spiro** Department of Chemistry, Princeton University, Princeton, New Jersey 08544-1009 Received December 1, 1988; Revised Manuscript Received February 22, 1989 abstract: Ultraviolet resonance Raman spectra are reported for cytochrome c (cyt c) in Fe11 and Fe111 oxidation states atlow (0.005 M) and high (0.9-1.5 M) ionic strength. With 200-nm excitation the amide band intensities are shown to remain constant, establishingthat redoxstate and ionic strength have no influence on the-helical content. The tyrosine 830/850-cm" 1 doublet, however, shows a loss in 830-cm" 1 intensity at I= 0.005 M for the Fe111 protein, suggesting a weakening or a loss of H-bonding from an internal tyrosine, probably Tyr-48, which is H-bonded to a heme propionate group in cyt c crystals. Excitation profiles of tryptophan peak at~ 229 nm for both Fe11 and Fe111 forms of cyt c, but at~ 218 nm for aqueous tryptophan. The~ 2200-cm'1 red shift of the resonant electronic transition is attributed to the Trp-59 residue being buried and H-bonded. Consistent with this Trp environment, the H-bond-sensitive 877-cm" 1 Trp band is strong and sharp, and the 1357/1341-cm" 1 doublet has a large intensity ratio,—1.5, for both Fe11 and Fe111 cyt c. The 877-cm" 1-band frequency shifts to 860 cm'1 when the Trp indole proton is replaced by a deuteron. This band was used to show that Trp H/D exchange in D20 is much faster for Fe111 than Fe11 cyt c. The half-time for exchange at room temperature is estimated to be~ 30 and-~ 5 h, respectively, for Fe11 and Fe111 when examined at I=0.005. Increasing the ionic strength to 1.5 M, however, raises the half-time to~ 30 h for Fe111 cyt c and to a much larger value for the Fe11 cyt c. This variation in the protein dynamics is consistent with recent evidence that the radius of gyration of the Fe111 protein increases with decreasing ionic strength (Trewhella et al., 1988).