期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：3
页码：900-904
DOI：10.1073/pnas.89.3.900
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Photolyases repair pyrimidine dimers in DNA by converting the light energy of 300- to 500-nm photons into chemical energy. Enzymes from various organisms contain two chromophore cofactors (FADH2 and either methenyltetrahydrofolate or 8-hydroxy-5-deazaflavin) that absorb the low-energy photons and initiate splitting of the cyclobutane ring by a radical mechanism. Here, we show that, in addition to these two chromophores, in the far UV range, direct excitation of one specific tryptophan residue (out of 15 total) in the polypeptide chain of Escherichia coli photolyase leads to splitting of the cyclobutane ring with high quantum yield (phi = 0.56), independent of the other chromophores. The specific tryptophan residue responsible for photosensitized repair was identified as Trp-277 by site-specific mutagenesis.
