Anisotropic rotational diffusion of perdeuterated HIV protease from 15N NMR relaxation measurements at two magnetic fields
Anisotropic rotational diffusion of perdeuterated HIV protease from 15N NMR relaxation measurements at two magnetic fields
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来自两个磁场下 15N NMR 弛豫测量的全氘化 HIV 蛋白酶的各向异性旋转扩散
作者：
N. Tjandra;P. Wingfield;S. Stahl;A. Bax
摘要 已在 600 和 360 MHz 1H 频率下测量了与亚纳摩尔抑制剂 DMP323 复合的全氘化 HIV-1 蛋白酶的 15 N NMR 弛豫时间。根据蛋白质-药物复合物的 X 射线坐标计算，惯性张量主成分的相对大小为 1.0:0.85:0.44。观察到的各个主链酰胺的 T1/T2 比率与其在蛋白酶二聚体 3D 结构内的 N-H 取向之间的关系产生了与惯性张量几乎共线取向的旋转扩散张量。其主成分的相对大小（1.00：1.11：1.42）也与水动力模拟结果非常吻合。从 360 和 600 MHz 获得的弛豫数据得出的扩散张量的方向和大小几乎相同。旋转扩散的各向异性本质对由 15N T1 和 T2 弛豫时间导出的有序参数影响不大；然而，如果忽略各向异性，这可能会导致纳秒时间尺度上的交换展宽或内部运动的错误识别。在 360 和 600 MHz 测量的 T1 值的平均比率为 0.50±0.015，略大于 τc = 10.7 ns 的各向同性刚性转子的预期值 0.466。在 360 MHz 和 600 MHz 测量的 T2 值的平均比率为 1.14±0.04，也略大于预期比率 1.11。 T1 和 T2 弛豫时间的磁场依赖性表明，快速内部运动的谱密度贡献不可忽略，并且肽骨架酰胺的化学位移各向异性平均大于蛋白质 15N 弛豫研究中常用的 160 ppm 值。
Summary15N NMR relaxation times in perdeuterated HIV-1 protease, complexed with the sub-nanomolar inhibitor DMP323, have been measured at 600 and 360 MHz 1H frequency. The relative magnitudes of the principal components of the inertia tensor, calculated from the X-ray coordinates of the protein-drug complex, are 1.0:0.85:0.44. The relation between the T1/T2 ratios observed for the individual backbone amides and their N-H orientation within the 3D structure of the protease dimer yields a rotational diffusion tensor oriented nearly collinear to the inertia tensor. The relative magnitudes of its principal components (1.00:1.11:1.42) are also in good agreement with hydrodynamic modeling results. The orientation and magnitude of the diffusion tensors derived from relaxation data obtained at 360 and 600 MHz are nearly identical. The anisotropic nature of the rotational diffusion has little influence on the order parameters derived from the 15N T1 and T2 relaxation times; however, if anisotropy is ignored, this can result in erroneous identification of either exchange broadening or internal motions on a nanosecond time scale. The average ratio of the T1 values measured at 360 and 600 MHz is 0.50±0.015, which is slightly larger than the value of 0.466 expected for an isotropic rigid rotor with τc = 10.7 ns. The average ratio of the T2 values measured at 360 and 600 MHz is 1.14±0.04, which is also slightly larger than the expected ratio of 1.11. This magnetic field dependence of the T1 and T2 relaxation times suggests that the spectral density contribution from fast internal motions is not negligible, and that the chemical shift anisotropy of peptide backbone amides, on average, is larger than the 160 ppm value commonly used in 15N relaxation studies of proteins.
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DOI：
10.1111/j.1432-1033.1995.1014g.x
发表时间：
1995-06
期刊：
European journal of biochemistry
影响因子：
--
作者：
Nico Tjandra;Hitoshi Kuboniwa;Hao Ren;Ad Bax
通讯作者：
Nico Tjandra;Hitoshi Kuboniwa;Hao Ren;Ad Bax
无模型公式的检验。
DOI：
10.1006/jmrb.1994.1127
发表时间：
1994
期刊：
Journal of magnetic resonance. Series B
影响因子：
--
作者：
Schurr,JM;Babcock,HP;Fujimoto,BS
通讯作者：
Fujimoto,BS
影响因子：
2.9
作者：
PENG, JW;WAGNER, G
通讯作者：
WAGNER, G
通过二维质子检测 15N NMR 光谱研究负载钙的钙结合蛋白 D9k 的主链动力学。
影响因子：
2.9
作者：
Kördel,J;Skelton,NJ;Akke,M;Palmer3rd,AG;Chazin,WJ
通讯作者：
Chazin,WJ
影响因子：
2.9
作者：
SCHNEIDER, DM;DELLWO, MJ;WAND, AJ
通讯作者：
WAND, AJ