Backbone dynamics of deoxy and carbonmonoxy hemoglobin by NMR/SRLS.
Backbone dynamics of deoxy and carbonmonoxy hemoglobin by NMR/SRLS.
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DOI：
10.1021/jp107553j
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发表时间：
2011-01-13
影响因子：
3.3
通讯作者：
Freed, Jack H.
中科院分区：
文献类型：
--
作者：
Meirovitch, Eva;Zerbetto, Mirco;Polimeno, Antonino;Freed, Jack H.
本文将缓慢弛豫局部结构(SRLS)方法应用于蛋白质的核磁共振自旋弛豫分析，研究了脱氧和一氧化碳血红蛋白中的酰胺15N驰豫。分析了在11.7℃和14.1T、29℃和34℃下获得的15N T1、T2和15N-1H}NOE等实验数据。用轴向局域有序张量S的主值()和取向(βD)和轴向局部扩散张量的主值(和)和取向(βO)描述了N-H键的限制局域运动。参数(定义的势系数)，βD和βO是通过数据拟合确定的，它等于在所研究的温度范围内以前发现的全球运动速率RC为(5.2-5.8)×10 6 1/S。S的主轴与主轴(几乎)平行；当两轴平行时，βD=−101.3°(在所用的框架中)。RL的主轴(几乎)平行于N-H键；当两轴平行时，βO=−101.3°。对于位于二级结构单元中的“刚性”N-H键，最适合的参数为(对应于8.6KBT-19.9KBT的局域势)，βD=−101.3°±2.0°，βO=−101.3°±4°。对于位于环中的柔性N-H键，最佳拟合值为(对应于4.5KBT的局域电位)，βD=−101.3°±4.0°，βO=−101.3°±10°。鉴于这些结果的物理清晰度、进一步解释的内在潜力、一致性和提供的新的定性见解(见下文)，这些结果是重要的。
The slowly relaxing local structure (SRLS) approach, developed for NMR spin relaxation analysis in proteins, is applied herein to amide 15N relaxation in deoxy and carbonmonoxy hemoglobin. Experimental data including 15N T1, T2 and 15N–{1H} NOE, acquired at 11.7 and 14.1 T, and 29 and 34 °C, are analyzed. The restricted local motion of the N–H bond is described in terms of the principal value ( ) and orientation (βD) of an axial local ordering tensor, S, and the principal values ( and ) and orientation (βO) of an axial local diffusion tensor, RL. The parameters (the potential coefficient in terms of which is defined), , βD and βO are determined by data fitting; is set equal to the global motional rate, RC, found previously to be (5.2–5.8)×106 1/s in the temperature-range investigated. The principal axis of S is (nearly) parallel to the axis; when the two axes are parallel βD = −101.3° (in the frame used). The principal axis of RL is (nearly) parallel to the N–H bond; when the two axes are parallel βO = −101.3°. For “rigid” N–H bonds located in secondary structure elements the best-fit parameters are (corresponding to local potentials of 8.6–19.9 kBT), , βD = −101.3° ± 2.0° and βO = −101.3° ± 4°. For flexible N–H bonds located in loops the best-fit values are (corresponding to local potentials of 4.5–5.5 kBT), , βD = −101.3° ± 4.0° and βO = −101.3° ± 10°. These results are important in view of their physical clarity, inherent potential for further interpretation, consistency, and new qualitative insights provided (vide infra).
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