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EFFECTS OF SENSITIZED AND UNSENSITIZED LONGWAVE U.V.‐IRRADIATION ON THE SOLUTION PROPERTIES OF DNA
Author(s) -
ZIERENBERG B. E.,
KRÄMER D. M.,
GEISERT M. G.,
KIRSTE R. G.
Publication year - 1971
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.1751-1097.1971.tb06190.x
Subject(s) - thymine , chemistry , hyperchromicity , dna , aqueous solution , irradiation , photochemistry , acetophenone , photosensitizer , radius of gyration , benzophenone , organic chemistry , biochemistry , polymer , physics , nuclear physics , catalysis
— Two types of photoreactions occur in DNA irradiated in aqueous systems with longwave u.v.‐light (Λ > 295 nm), namely, (a) thymine dimerization, and (b) single‐ and double‐strand breakage of the sugar phosphate backbone; these two reactions are unrelated. The presence of acetophenone as a photosensitizer caused an increase in dimerization by a factor of 16, and an increase in single‐strand breaks by a factor of 4. The number of thymine dimers per single‐strand break is about 100 in the sensitized and 25 in the unsensitized reaction. The alteration of the radius of gyration of DNA molecules is that expected by the degradation observed. At the same time the change in hyperchromicity is very small. Therefore as far as can be detected by these methods of investigation the gross conformation of the DNA double helix is stable against thymine dimerization.