RELATIVE CONTRIBUTIONS OF CHEMICAL-EXCHANGE AND OTHER RELAXATION MECHANISMS IN PROTEIN SOLUTIONS AND TISSUES
RELATIVE CONTRIBUTIONS OF CHEMICAL-EXCHANGE AND OTHER RELAXATION MECHANISMS IN PROTEIN SOLUTIONS AND TISSUES
复制标题
DOI：
10.1002/mrm.1910110304
复制
发表时间：
1989-09-01
影响因子：
3.3
通讯作者：
ARMITAGE, IM
中科院分区：
文献类型：
--
作者：
ZHONG, JH;GORE, JC;ARMITAGE, IM
测量了在不同静磁场（0.15 ~ 11 T）下，5%蛋白质溶液和大鼠肝脏中水质子的横向弛豫时间T2。蛋白质分子量在1.4和480 kDa之间变化，在不同程度的氘化的解决方案。所获得的数据进行了分析的模型系统，包括三个阶段的不同的弛豫特性：蛋白质质子，水化层水质子，和散装水质子。由于水质子的流体动力学效应，水化层水质子和蛋白质质子之间的交叉弛豫，和水化层水质子和散装水质子之间的化学交换的弛豫的贡献分别估计。实验结果表明，在大鼠肝脏和所研究的所有蛋白质中，“流体动力学相互作用”的大小大致相同，但在不同的蛋白质体系中，交叉弛豫的贡献相差几个数量级。水合层水和散装水之间的快速化学交换导致相当大的缩短T2在高磁场的所有蛋白质溶液和大鼠组织的研究。在不同温度（213-318 K 0）和CPMG序列中的不同间隔下研究了选定的样品。化学交换率和不同相的分数种群的确定，并获得的结果提供支持的模型中，不同的水相之间的快速交换是一个重要的特征的整体松弛行为。
Transverse relaxation times T2 of water protons were measured in 5% protein solutions and soaked rat liver in different static magnetic fields (0.15 to 11 T). Protein molecular weight varied between 1.4 and 480 kDa in solutions of varying degrees of deuteration. The data obtained are analyzed in terms of a model system consisting of three phases of different relaxation characteristics: protein protons, hydration layer water protons, and bulk water protons. The contributions to relaxation due to hydrodynamic effects on water protons, cross relaxation between the hydration layer water protons and the protein protons, and chemical exchange between the hydration layer water protons and the bulk water protons are separately estimated. The experimental results indicate that the "hydrodynamic interactions" are about the same magnitude in rat liver and all the proteins studied, but the contribution of the cross relaxation differs by several orders in different proteins systems. Fast chemical exchange between the hydration layer water and the bulk water causes considerable shortening of T2 at high magnetic fields for all protein solutions and rat tissue studied. Selected samples were studied at different temperatures (213-318 K0 and with different intervals in the CPMG sequence. The rates of chemical exchange and fractional populations of different phases are determined, and the results obtained provide support for the model in which fast exchange among the different water phases is an important feature of the overall relaxation behavior.