Daragan V A, Kloczewiak M A, Mayo K H
Department of Biochemistry, Biomedical Engineering Center, University of Minnesota, Minneapolis 55455.
Biochemistry. 1993 Oct 12;32(40):10580-90. doi: 10.1021/bi00091a007.
Spin-lattice relaxation of 13C multiplet spectra and [1H]-13C nuclear Overhauser enhancement (NOE) coefficients of selectively 13C-enriched glycines in a collagen GXX-repeat motif hexadecapeptide, G1VKG4DKG7NPG10WPG13APY, has been investigated. Data have been collected at two 13C Larmor frequencies (90 and 150 MHz) over the temperature range from 5 to 70 degrees C. Relaxation data indicate that the most restricted internal rotations are at G7 and G10. Mobility of other glycine residues can be arranged in the order G4, G13, and G1. G1 glycine shows that least change in motional anisotropy with temperature. Several motional models have been used to explain the experimental data. While any one model is not completely satisfactory in describing all experimental parameters, only the model of restricted internal diffusion yields the observed positive sign for the cross-correlated spectral densities. Energetic and angular limits of psi, phi bond rotational motions derived from relaxation data and the restricted diffusion model are in good agreement with those calculated as Ramachandran potentional energy profiles. G1 rotational energy barriers for overall tumbling and internal rotation are approximately equal, suggesting strong interaction between the N-terminus and water. Internal rotational parameters for GV and GG dipeptides confirm this view. Nonterminal glycine internal motions are apparently less dependent on water-peptide interactions.
对胶原蛋白GXX重复基序十六肽G1VKG4DKG7NPG10WPG13APY中选择性13C富集甘氨酸的13C多重峰光谱的自旋-晶格弛豫和[1H]-13C核Overhauser增强（NOE）系数进行了研究。在5至70摄氏度的温度范围内，于两个13C拉莫尔频率（90和150 MHz）下收集了数据。弛豫数据表明，最受限的内部旋转发生在G7和G10处。其他甘氨酸残基的流动性可按G4、G13和G1的顺序排列。G1甘氨酸显示出运动各向异性随温度的变化最小。已使用多种运动模型来解释实验数据。虽然任何一个模型在描述所有实验参数时都不完全令人满意，但只有受限内部扩散模型产生了观察到的交叉相关光谱密度的正号。从弛豫数据和受限扩散模型得出的ψ、φ键旋转运动的能量和角度极限与作为拉马钱德兰势能分布计算出的结果高度一致。G1的整体翻滚和内部旋转的旋转能垒大致相等，表明N端与水之间存在强相互作用。GV和GG二肽的内部旋转参数证实了这一观点。非末端甘氨酸的内部运动显然较少依赖于水-肽相互作用。
