Quantifying protein dynamics in the ps-ns time regime by NMR relaxation.
Quantifying protein dynamics in the ps-ns time regime by NMR relaxation.
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DOI：
10.1007/s10858-016-0064-7
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发表时间：
2016-11
影响因子：
2.7
通讯作者：
LeMaster DM
中科院分区：
文献类型：
--
作者：
Hernández G;LeMaster DM
15N化学位移各向异性（CSA）和足够快的交换线加宽过渡表现出弛豫贡献，是成比例的磁场的平方。去卷积这些贡献是进一步复杂的蛋白酰胺15 N CSA值的残基依赖性的变化，已被证明难以准确测量。利用最近报道的T1和T1ρ实验的改进，已经对蛋白G（GB3）的B3结构域以及亲免素FKBP 12和该蛋白的H87 V变体进行了场强依赖性研究，其中主要的构象交换谱线加宽转变被抑制。通过应用零频谱密度重新标度分析，在磁场从500 MHz 1H到900 MHz 1H收集的弛豫数据，差分残留特定的15 N CSA值已获得GB3与来自固态和液晶NMR测量的相关性类似的水平，这些先前报道的研究之间的相关性。该分析方案的应用FKBP 12证明了一个有效的定量弱交换线加宽的贡献和差分残留特定的15 N CSA值。实验访问这样的差分残基特定的15 N CSA值应显着促进更准确的比较与分子动力学模拟的蛋白质运动发生在全球分子翻滚的时间范围内。
Both 15N chemical shift anisotropy (CSA) and sufficiently rapid exchange linebroadening transitions exhibit relaxation contributions that are proportional to the square of the magnetic field. Deconvoluting these contributions is further complicated by residue-dependent variations in protein amide 15N CSA values which have proven difficult to accurately measure. Exploiting recently reported improvements for the implementation of T1 and T1ρ experiments, field strength-dependent studies have been carried out on the B3 domain of protein G (GB3) as well as on the immunophilin FKBP12 and a H87V variant of that protein in which the major conformational exchange linebroadening transition is suppressed. By applying a zero frequency spectral density rescaling analysis to the relaxation data collected at magnetic fields from 500 MHz 1H to 900 MHz 1H, differential residue-specific 15N CSA values have been obtained for GB3 which correlate with those derived from solid state and liquid crystalline NMR measurements to a level similar to the correlation among those previously reported studies. Application of this analysis protocol to FKBP12 demonstrated an efficient quantitation of both weak exchange linebroadening contributions and differential residue-specific 15N CSA values. Experimental access to such differential residue-specific 15N CSA values should significantly facilitate more accurate comparisons with molecular dynamics simulations of protein motion that occurs within the timeframe of global molecular tumbling.