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INFLUENCE OF pH AND OXYGEN ON 315 mμ INACTIVATION AND THYMINE DIMERIZATION IN MUTANTS OF BACTERIOPHAGE T4
Author(s) -
Haug A.,
Sauerbier W.
Publication year - 1965
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.1751-1097.1965.tb09773.x
Subject(s) - thymine , photolyase , cytosine , pyrimidine dimer , chemistry , dna , dimer , oxygen , bacteriophage , photochemistry , guanine , mutant , stereochemistry , nuclear chemistry , medicinal chemistry , nucleotide , biochemistry , dna damage , dna repair , organic chemistry , escherichia coli , gene
— 1. Irradiation with 315 mμ light inactivates phage T4v‐x C, and T4v ‐ x‐ , and forms thymine dimers in their DNA. 2. Both the rates of inactivation and of thymine dimerization depend upon pH and gaseous environment during irradiation. The U.V. sensitivities are: 1 (pH 7, N 2 , 03, 2.2 (pH 3.5, Oz), 3.3 (pH 3–5, N 2 ; and the corresponding rates of thymine dimerization 1: 2.5: 5.2. The number of thymine dimers per lethal hit observed withT4v‐x + are: 5.7 (pH 7, N 2 , O 2 , 5.4 (pH 3.5, O 2 , 10.9 (pH 3.5, N 2 ); and forT4v‐x‐: 4.6, 3.4, and 7.1 with the same sequence of conditions. 3. Also the photoreactivable sectors depend upon the environmental conditions at 315 mp inactivation. In T4v‐x f this sector amounts to about 50 per cent at pH 7, 18 per cent at pH 3.5, O., and 29 per cent at pH 3.5, N, respectively. 4. The molecular basis of these findings is discussed. It is concluded that, besides thymine dimer, at least one other lethal photoproduct (probably a photoproduct of cytosine) is involved in photoreactivation.