PHOTOPHYSICS OF TRYPTOPHAN IN BACTERIOPHAGE-T4 LYSOZYMES
PHOTOPHYSICS OF TRYPTOPHAN IN BACTERIOPHAGE-T4 LYSOZYMES
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DOI：
10.1021/bi00474a009
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发表时间：
1990-06-05
期刊：
影响因子：
2.9
通讯作者：
HUDSON, BS
中科院分区：
文献类型：
--
作者：
HARRIS, DL;HUDSON, BS
噬菌体T4溶菌酶在不同的环境中含有三种色氨酸残基。一个或两个这些残基被酪氨酸取代的溶菌酶被用来表征色氨酸在这些单个位点上的光物理特性。这三种单色氨酸变体的荧光光谱、平均寿命和量子产率根据邻近残基是可以理解的。发现这三种物质的发射光谱和辐射寿命相同，而量子产率和衰变动力学却截然不同。平均非辐射速率常数的变化与邻近的猝灭基团有关。根据晶体结构，I-猝灭与色氨酸残基暴露有关。在所有三种情况下，包括固定色氨酸-138残基，观察到荧光衰减的时间依赖性的复杂行为。荧光衰减的复杂性归因于微观状态间非辐射速率常数的异质性。色氨酸残基之间的能量转移是从比较双色氨酸和单色氨酸蛋白质的量子产率推断出来的，并根据福斯特机制进行了讨论。
Bacteriophage T4 lysozyme contains three tryptophan residues in distinct environments. Lysozymes with one or two of these residues replaced by tyrosine are used to characterize the photophysics of tryptophan in these individual sites. The fluorescence spectra, average lifetimes, and quantum yields of these three single-tryptophan variants are understandable in terms of the neighboring residues. The emission spectra and radiative lifetimes are found to be the same for all three species while the quantum yield and decay kinetics are quite distinct. The variation of the average nonradiative rate constant is correlated with neighboring quenching groups. Quenching by I- correlates with exposure of the tryptophan residue based on the crystal structure. Complex behavior is observed for the time dependence of the fluorescence decay in all three cases, including that of the immobile tryptophan-138 residue. The complexity of the fluorescence decay is ascribed to heterogeneity in the nonradiative rate constant among microstates. Energy transfer between tryptophan residues is inferred to occur from comparison of the quantum yields of the two-tryptophan and single-tryptophan proteins and is discussed in terms of the Forster mechanism.