Time-resolved fluorescence and 1H NMR studies of tyrosine and tyrosine analogues: correlation of NMR-determined rotamer populations and fluorescence kinetics.
Time-resolved fluorescence and 1H NMR studies of tyrosine and tyrosine analogues: correlation of NMR-determined rotamer populations and fluorescence kinetics.
复制标题
酪氨酸和酪氨酸类似物的时间分辨荧光和 1H NMR 研究：NMR 测定的旋转异构体群与荧光动力学的相关性。
DOI：
10.1021/bi00351a013
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发表时间：
1986
期刊：
影响因子：
2.9
通讯作者：
Sutherland,JC
中科院分区：
文献类型：
--
作者：
Laws,WR;Ross,JB;Wyssbrod,HR;Beechem,JM;Brand,L;Sutherland,JC
苯酚和直链苯酚衍生物和酪氨酸和简单的酪氨酸衍生物的时间分辨荧光性质的报告低于中性的pH范围。苯酚和直链苯酚衍生物在此pH范围内表现出单指数荧光衰减动力学，除非它们具有可滴定的羧基。如果存在羧基，则数据遵循两态、基态、Henderson-Hasselbalch关系。酪氨酸及其衍生物与一个自由的羧基显示复杂的fluorescencedecay行为作为pH值的函数。复杂的动力学不能完全解释滴定的羧基，其他基态过程是显而易见的，特别是因为酪氨酸类似物与一个封闭的羧基也是多指数。荧光动力学可以用基态旋转异构体模型来解释。指前加权因子的比较用NMR测定的酚侧链旋转异构体群体的荧光衰减常数（振幅）表明（1）具有封闭或质子化羧基的酪氨酸衍生物具有比辐射和非辐射速率更慢的至少一种旋转异构体交换，并且荧光数据与所有三种旋转异构体的慢交换模型一致，（2）最短的荧光衰减常数与其中羰基可以接触酚环的旋转异构体有关，和（3）在酪氨酸两性离子中，或者旋转异构体互变快并且观察到平均寿命，或者旋转异构体互变慢并且各个荧光衰减常数相似。蛋白质的分辨荧光主要与色氨酸有关。相比之下，酪氨酸受到的关注要少得多，这是由于其吸收率相对较低，当掺入多肽链中时量子产率较低[参见Longworth的综述（1971，1983）]，拉曼散射干涉作为小荧光斯托克斯位移的结果，色氨酸掩蔽酪氨酰发射，以及激发态质子转移与酪氨酸构象形成的可能性，使衰变动力学（Laws & Brand，1979）和光谱特性复杂化
The time-resolved fluorescence properties of phenol and straight-chained phenol derivatives and tyrosine and simple tyrosine derivatives are reported for the pH range below neutrality. Phenol and straight-chained phenol derivatives exhibit single exponential fluorescence decay kinetics in this pH range unless they have a titratable carboxyl group. If a carboxyl group is present, the data follow a two-state, ground-state, Henderson-Hasselbalch relationship. Tyrosine and its derivatives with a free carboxyl group display complex fluorescencedecay behavior as a function of pH. The complex kinetics cannot be fully explained by titration of a carboxyl group; other ground-state processes are evident, especially since tyrosine analogues with a blocked carboxyl group are also multiexponential. The fluorescence kinetics can be explained by a ground-state rotamer model. Comparison of the preexponential weighting factors (amplitudes) of the fluorescence decay constants with the NMR determined phenol side-chain rotamer populations shows that (1) tyrosinederivatives with a blocked or protonated carboxyl group have at least one rotamer exchanging more slowly than the radiative and nonradiative rates, and the fluorescence data are consistent with a slow-exchange model for all three rotamers,(2) the shortest fluorescence decay constant is associated with a rotamer where the carbonyl group can contact the phenol ring, and (3) in the tyrosine zwitterion, either rotamer interconversion is fast and an average lifetime is seen or rotamer interconversion is slow and the individual fluorescence decay constants are similar.Aime-resolved fluorescence of proteins has mainly been concerned with tryptophan. Tyrosine, by comparison, has received much less attention due to its relatively low absorp-tivity, low quantum yield when incorporated in polypeptide chains [see reviews by Longworth (1971, 1983)], Raman scatter interference as a consequence of the small fluorescence Stokes shift, masking of the tyrosyl emission by tryptophan, and the possibility of excited-state proton transfer with con-comitant formation of tyrosinate complicating the decay ki-netics (Laws & Brand, 1979) and spectral characteristics