PHOTOCHEMICAL COUPLING OF 5-BROMOURACIL TO TRYPTOPHAN, TYROSINE AND HISTIDINE, PEPTIDE-LIKE DERIVATIVES IN AQUEOUS FLUID SOLUTION
PHOTOCHEMICAL COUPLING OF 5-BROMOURACIL TO TRYPTOPHAN, TYROSINE AND HISTIDINE, PEPTIDE-LIKE DERIVATIVES IN AQUEOUS FLUID SOLUTION
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DOI：
10.1111/j.1751-1097.1987.tb04879.x
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发表时间：
1987-12-01
影响因子：
3.3
通讯作者：
KOCH, TH
中科院分区：
文献类型：
--
作者：
DIETZ, TM;KOCH, TH
在色氨酸（trp）、酪氨酸（tyr）或组氨酸（his）衍生物存在下，用XeCl准分子激光器在308 nm处直接照射5-溴尿嘧啶（BU）水溶液，使BU与每个氨基酸的芳环发生光偶联。在308 nm下照射BU最可能导致n-π * 的激发。跃迁、系间交叉至三重态歧管以及通过芳香族氨基酸的电子转移偶联。观察到的偶联在尿嘧啶（U）的5-位与吲哚和苯酚环的2-位以及相应氨基酸的咪唑环的5-位之间具有区域特异性。与BU的光耦合的量子产率范围为1 × 10 - 4。10-3以及已知的芳环的电子转移速率和电离电势。BU和一些芳香族氨基酸肽类衍生物之间的光偶联可能模拟BU-DNA与相关蛋白质的光交联，这是一种用于研究核酸-蛋白质相互作用的潜在有用的光反应。这里提出的类型的交联的形成可以通过尿嘧啶氨基酸加合物的特征荧光发射来检测。
Direct irradiation of 5-bromouracil (BU) in aqueous fluid solution in the presence of tryptophan (trp), tyrosine (tyr) or histidine (his) derivatives using a XeCl excimer laser at 308 nm yielded photocoupling of BU to the aromatic ring of each amino acid. Irradiation of BU at 308 nm most likely results in excitation of the n-.pi.* transition, intersystem crossing to the triplet manifold, and coupling via electron transfer from the aromatic amino acid. The coupling observed was regiospecific between the 5-position of uracil (U) and the 2-position of the indole and phenol rings and the 5-position of the imidazole ring of the respective amino acids. Quantum yields of photocoupling to BU ranged from 1 .times. 10-3 and paralleled known rates of electron transfer and ionization potentials of the aromatic rings. The photocoupling between BU and some of the aromatic amino acid peptide-like derivatives possibly mimics photocrosslinking of BU-DNA to associated proteins, a potentially useful photoreaction for studying nucleic acid-protein interactions. Formation of crosslinks of the type proposed here might be detected by the characteristic fluorescence emission of the uracil amino acid adducts.