PROTEIN ROTATIONAL RELAXATION AS STUDIED BY SOLVENT H-1 AND H-2 MAGNETIC-RELAXATION
PROTEIN ROTATIONAL RELAXATION AS STUDIED BY SOLVENT H-1 AND H-2 MAGNETIC-RELAXATION
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DOI：
10.1021/bi00664a019
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发表时间：
1976-01-01
期刊：
影响因子：
2.9
通讯作者：
KOENIG, SH
中科院分区：
文献类型：
--
作者：
HALLENGA, K;KOENIG, SH
早期的研究磁场依赖性的反磁性蛋白质溶液中的溶剂质子的核自旋磁弛豫速率已经表明，这种依赖性（称为弛豫分散）与溶质蛋白质的旋转布朗运动。实质上，色散使得1/T1（质子自旋-晶格弛豫速率）随着磁场从非常低的值（apx）增加而单调减小。10 Oe [oerstedt]）;分散体在磁场值处具有拐点，该磁场值取决于蛋白质的大小、形状、浓度、温度和溶剂组成。质子拉莫尔旋进频率nuc在拐点场中的值似乎与蛋白质分子的旋转弛豫时间τ R相关。质子弛豫分散测量的各种蛋白质的溶液，跨越三十个十年的分子量范围，并为1个样本的tRNA。还测量了3种蛋白质的溶液的氘弛豫分散体：溶菌酶、碳一氧血红蛋白和分子量为900，000的Hispomatia血蓝蛋白。本文证实了质子和氘的磁散人数据与蛋白质转动弛豫之间的定量关系，指出磁散人测量对于测量溶液中大分子的转动弛豫速率具有非常普遍的适用性。先前已经表明，质子运动对溶剂的弛豫行为的影响不是由于本体溶剂和蛋白质的水合区域之间的溶剂分子的交换。本文认为，这种相互作用的结果从一个长期的流体动力学效应的基本情况下，大布朗粒子在一个基本上连续的流体。所提出的机制的一般特点表明，但没有理论计算。
Earlier studies of the magnetic field dependence of the nuclear spin magnetic relaxation rate of solvent protons in solutions of diamagnetic proteins have indicated that this dependence (called relaxation dispersion) is related to the rotational Brownian motion of solute proteins. In essence the dispersion is such that 1/T1 (the proton spin-lattice relaxation rate) decreases monotonically as the magnetic field is increased from a very low value (.apprx. 10 Oe [oerstedt]); the dispersion has a point of inflection at a value of magnetic field which depends on protein size, shape, concentration, temperature and solvent composition. The value of the proton Larmor precession frequency .nu.c at the inflection field appears to relate to .tau.R, the rotational relaxation time of the protein molecules. Proton relaxation dispersions were measured for solutions of various proteins that span a three-decade range of molecular weights, and for 1 sample of tRNA. Deuteron relaxation dispersions were also measured for solutions of 3 proteins: lysozyme, carbonmonoxyhemoglobin and Helix pomatia hemocyanin with MW 900,000. A quantitative relationship between both proton and deuteron disperson data and protein rotational relaxation is confirmed, and the point is made that magnetic disperson measurements are of very general applicability for measuring the rotational relaxation rate of macromolecules in solution. It has been previously shown that the influence of proton motion on the relaxation behavior of the solvent is not due to exchange of solvent molecules between the bulk solvent and a hydration region of the protein. The present paper suggests that the interaction results from a long range hydrodynamic effect fundamental to the situation of large Brownian particles in an essentially continuum fluid. The general features of the proposed mechanism are indicated, but no theoretical computations are presented.