Gryczynski I, Eftink M, Lakowicz J R
University of Maryland, Baltimore School of Medicine, Department of Biological Chemistry 21201.
Biochim Biophys Acta. 1988 Jun 13;954(3):244-52. doi: 10.1016/0167-4838(88)90079-9.
We examined the frequency-domain intensity decays of the intrinsic tryptophan fluorescence (Trp-59) from ribonuclease T1 (EC 3.1.27.3) (RNAase T1). At pH 5.5 in the native state (below 30 degrees C), the intensity decay of the single tryptophan residue is a single-exponential process. Conditions which result in protein unfolding were found to induce more complex intensity decays. At temperatures above 40 degrees C, or in the presence of guanidine hydrochloride, the intensity decays became obviously double exponential. In general, the main effect of temperature or guanidine was to induce a second subnanosecond component in the intensity decay. The increased complexity of the decays could not be explained by a unimodal distribution of decay times. These results indicate that conformational dispersion of protein structure can be one origin of the multi-exponential decays which are generally observed for protein fluorescence.
我们研究了核糖核酸酶T1（EC 3.1.27.3）（RNAase T1）中内在色氨酸荧光（Trp-59）的频域强度衰减。在pH 5.5的天然状态下（低于30摄氏度），单个色氨酸残基的强度衰减是单指数过程。发现导致蛋白质去折叠的条件会诱导更复杂的强度衰减。在40摄氏度以上的温度下，或在存在盐酸胍的情况下，强度衰减明显变为双指数。一般来说，温度或胍的主要作用是在强度衰减中诱导出第二个亚纳秒成分。衰减复杂性的增加不能用衰减时间的单峰分布来解释。这些结果表明，蛋白质结构的构象分散可能是蛋白质荧光通常观察到的多指数衰减的一个起源。
