Anisotropic rotational motions of poly(L‐glutamic acid) in the α‐helix conformation
Anisotropic rotational motions of poly(L‐glutamic acid) in the α‐helix conformation
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α-螺旋构象中聚（L-谷氨酸）的各向异性旋转运动
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
H. Rüterjans
中科院分区：
文献类型：
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作者：
U. Hahn;H. Hanssum;H. Rüterjans
使用直接连接质子的所有碳原子的 13C-T1 和 T2 弛豫时间（在 67.89 MHz 的 13C-Larmor 频率下获得）研究了 α 螺旋结构中聚（L-谷氨酸）主链和侧链的各向异性旋转运动。核磁共振数据的评估是根据先前推导的各向异性扩散模型进行的，其中大分子被认为是刚性棒。主干的旋转由两个扩散常数 D1 和 D3 来表征，描述垂直于对称轴并围绕对称轴的旋转。 Cβ-亚甲基的额外内部运动被描述为在两个允许的旋转状态之间具有跳跃速率 k1 的跳跃过程。空间考虑表明禁止占据第三个旋转异构体位置。 Cγ-亚甲基的旋转被描述为围绕Cβ-Cγ键的一维扩散过程。对弛豫参数的温度依赖性的研究导致了动态参数的温度依赖性。根据这些数据确定活化能。将聚（L-谷氨酸）在 291 K 下获得的动态参数与之前聚（L-赖氨酸）研究的相应结果进行比较。
The anisotropic rotational motion of the backbone and the side chains of poly(L‐glutamic acid) in the α‐helical structure was investigated using the 13C‐T1 and T2 relaxation times of all carbon atoms with directly attached protons, obtained at a 13C‐Larmor frequency of 67.89 MHz. The evaluation of the nmr data was carried out according to the previously derived anisotropic diffusion model, in which the macromolecule is considered a rigid rod. The rotation of the backbone is characterized by two diffusion constants, D1 and D3, describing the rotation perpendicular to and around the symmetry axis. The additional internal motion of the Cβ‐methylene group is described as a jump process with a jump rate, k1, between two allowed rotametric states. Steric considerations indicate that the occupation of the third rotameric position is forbidden. The rotation of the Cγ‐methylene group is decribed as a one‐dimensional diffusion process around the Cβ–Cγ bond. Investigation of the temperature dependence of the relaxation parameters led to the temperature dependence of the dynamic parameters. Activation energies were determined from these data. The dynamic parameters obtained for poly(L‐glutamic acid) at 291 K are compared with the corresponding results of a previous study of poly(L‐lysine).