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：2019
卷号：116
期号：38
页码：18822-18826
DOI：10.1073/pnas.1909722116
出版社：The National Academy of Sciences of the United States of America
摘要：The UV photodissociation kinetics of tryptophan amino acid, Trp, attached to the membrane of bacteria, Escherichia coli and Bacillus subtilis , have been studied by means of normal and synchronous fluorescence. Our experimental data suggest that the fluorescence intensity of Trp increases during the first minute of irradiation with 250 nm to ∼ 280 nm, 7 mW/cm 2 UV light, and subsequently decreases with continuous irradiation. During this short, less than a minute, period of time, 70% of the 10 7 cell per milliliter bacteria are inactivated. This increase in fluorescence intensity is not observed when tryptophan is in the free state, namely, not attached to a protein, but dissolved in water or saline solution. This increase in fluorescence is attributed to the additional fluorescence of tryptophan molecules formed by protein unfolding, the breakage of the bond that attaches Trp to the bacterial protein membrane, or possibly caused by the irradiation of 2 types of tryptophan residues that photolyze with different quantum yields..
