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STUDIES ON THE UV PHOTODESTRUCTION OF PURINE FREE BASE IN AQUEOUS SOLUTIONS AT 77 and 298K
Author(s) -
Arce R.,
Beniatez S.,
Rivera E.,
Rivera M.
Publication year - 1982
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1982.tb02564.x
Subject(s) - chemistry , aqueous solution , photochemistry , yield (engineering) , purine , free base , irradiation , absorption (acoustics) , base (topology) , absorption spectroscopy , scavenger , radical , organic chemistry , materials science , mathematical analysis , salt (chemistry) , physics , mathematics , quantum mechanics , nuclear physics , metallurgy , enzyme , composite material
— The photodestruction of purine free base used as a model for the purine bases in DNA has been studied in order to better understand the effect of UV light on these molecules. Photodestruction yields have been determined in glassy aqueous solutions at 77 K and at room temperature at different pH's. The yield decreases in the order of 0.04, 0.01, 0.001 in 8 M NaOH, 8 M NaCIO 4 and 6 M H 3 PO 4 , respectively, while at room temperature the highest destruction yield is 0.005 for the unbuffered neutral solution. These yields have been determined by measuring the initial decrease in the purine absorption maximum as a function of irradiation time. During the illumination stable photoproducts, as well as reactive intermediates, such as trapped electrons, radical anions and cations, are formed and have been characterized from their absorption spectra. The addition of triplet quenchers and an electron scavenger resulted in a decrease in the yield, implying the participation of the purine triplet state and a radical anion in the reactions leading to the photodestruction of purine.