Shah N K, Ludescher R D
Department of Food Science and Center for Advanced Food Technology, Cook College, Rutgers University, New Brunswick, NJ 08903-0231.
Photochem Photobiol. 1993 Aug;58(2):169-74. doi: 10.1111/j.1751-1097.1993.tb09544.x.
Proteins exist in a predominantly aqueous solvent environment. Hydration of the protein surface significantly affects many aspects of the protein's structure and function; these effects may be related to the molecular dynamics of the protein. We have examined the influence of hydration on the internal dynamics of hen egg white lysozyme using room-temperature phosphorescence from the intrinsic tryptophan residues. Powders of lyophilized lysozyme were hydrated in a phosphorimeter using a flow system that allowed for continuous manipulation of relative humidity over the range 0-92%; this system allowed us to directly compare intensity differences that result from changes in hydration. Lysozyme phosphorescence intensity decreased as a function of hydration over the entire relative humidity range; the decrease was not linear but appeared to occur in distinct phases. The phosphorescence intensity decays were multiexponential over the hydration range studied, and hydration had the largest influence on the long lifetime component. These data suggest that the protein exists in multiple, static conformations in the dry state and that water binding to polar (as opposed to charged) sites on the protein surface induces local and/or global softening of the protein structure.
蛋白质主要存在于水性溶剂环境中。蛋白质表面的水合作用会显著影响蛋白质结构和功能的许多方面；这些影响可能与蛋白质的分子动力学有关。我们利用内在色氨酸残基的室温磷光，研究了水合作用对鸡蛋清溶菌酶内部动力学的影响。冻干溶菌酶粉末在磷光计中通过流动系统进行水合，该系统能够在0 - 92%的相对湿度范围内连续调节相对湿度；该系统使我们能够直接比较因水合作用变化而产生的强度差异。在整个相对湿度范围内，溶菌酶磷光强度随水合作用而降低；这种降低不是线性的，而是似乎分不同阶段发生。在所研究的水合范围内，磷光强度衰减是多指数的，并且水合作用对长寿命成分影响最大。这些数据表明，蛋白质在干燥状态下以多种静态构象存在，并且蛋白质表面极性（而非带电）位点上的水结合会诱导蛋白质结构的局部和/或整体软化。
