Hallenga K, Koenig S H
Biochemistry. 1976 Sep 21;15(19):4255-64. doi: 10.1021/bi00664a019.
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 (approximately 10 Oe); 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. We have measured proton relaxation dispersions for solutions of various proteins that span a three-decade range of molecular weights, and for one sample of transfer ribonucleic acid. We have also measured deuteron relaxation dispersions for solutions of three proteins: lysozyme, carbonmonoxyhemoglobin, and Helix pomatia hemocyanin with molecular weight 900 000. A quantitative relationship between both proton and deuteron dispersion data and protein rotational relaxation is confirmed, and the point is made that magnetic dispersion 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. In the present paper, we suggest 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.
早期对抗磁性蛋白质溶液中溶剂质子的核自旋磁弛豫率与磁场依赖性的研究表明，这种依赖性（称为弛豫色散）与溶质蛋白质的旋转布朗运动有关。本质上，色散表现为随着磁场从非常低的值（约10奥斯特）增加，1/T1（质子自旋 - 晶格弛豫率）单调下降；色散在一个取决于蛋白质大小、形状、浓度、温度和溶剂组成的磁场值处有一个拐点。拐点处质子拉莫尔进动频率ν(c)的值似乎与蛋白质分子的旋转弛豫时间τ(R)有关。我们测量了分子量跨度达三个数量级的各种蛋白质溶液以及一个转移核糖核酸样品的质子弛豫色散。我们还测量了三种蛋白质溶液的氘核弛豫色散：溶菌酶、一氧化碳血红蛋白和分子量为900000的紫贻贝血蓝蛋白。质子和氘核色散数据与蛋白质旋转弛豫之间的定量关系得到了证实，并且指出磁色散测量对于测量溶液中大分子的旋转弛豫率具有非常广泛的适用性。先前已经表明，质子运动对溶剂弛豫行为的影响不是由于溶剂分子在本体溶剂和蛋白质的水化区域之间的交换。在本文中，我们认为这种相互作用源于大布朗粒子在基本连续流体中的一种基本的长程流体动力学效应。文中指出了所提出机制的一般特征，但未给出理论计算。
