Eftink M R, Ghiron C A
Proc Natl Acad Sci U S A. 1975 Sep;72(9):3290-4. doi: 10.1073/pnas.72.9.3290.
The fluorescence of the supposedly buried tryptophan in ribonuclease T1 has been found to be collisionally quenched by acrylamide with a rate constant of 3 X 10(8) M--1 sec--1. Only a slight decrease in the quenching rate is observed upon a 5-fold increase in the viscosity of the solution. For this to be the case, the diffusion of the quencher must be limited by the protein matrix. To explain the process of diffusion through this complex material, the formation of "holes" in the lattice of a protein due to nanosecond fluctuations must be invoked. Thus, the dynamic character of a protein molecule is revealed. The quenching rate constant has an activation energy of 9 kcal/mol which can be used to characterize the nature of the cohesive forces in the microenvironment about the indole ring. The mechanical properties of a portion of a protein matrix can, therefore, be described as one would for a fluid.
已发现核糖核酸酶T1中假定被掩埋的色氨酸的荧光会被丙烯酰胺碰撞猝灭，猝灭速率常数为3×10⁸ M⁻¹ s⁻¹。溶液粘度增加5倍时，仅观察到猝灭速率略有下降。要出现这种情况，猝灭剂的扩散必定受到蛋白质基质的限制。为了解释通过这种复杂物质的扩散过程，必须借助由于纳秒级波动而在蛋白质晶格中形成的“空洞”。因此，揭示了蛋白质分子的动态特性。猝灭速率常数的活化能为9千卡/摩尔，这可用于表征吲哚环周围微环境中内聚力的性质。因此，蛋白质基质一部分的机械性能可以像描述流体那样来描述。
