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PHOTOSENSITIZATION OF SINGLE‐STRAND BREAKS IN pBR322 DNA BY ROSE BENGAL
Author(s) -
CIULLA THOMAS A.,
CAMP JOHN R.,
ROSENFELD EVAN,
KOCHEVAR IRENE E.
Publication year - 1989
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.1751-1097.1989.tb04109.x
Subject(s) - rose bengal , chemistry , oxygen , photochemistry , cleavage (geology) , quantum yield , kinetics , sodium azide , materials science , biochemistry , organic chemistry , fluorescence , physics , quantum mechanics , fracture (geology) , composite material
Rose bengal photosensitized the formation of frank single‐strand breaks (SSBs) in double‐stranded, supercoiled pBR322 DNA as measured by neutral agarose electrophoresis. The yield of SSBs followed first order kinetics with respect to light fluence and dye concentration. The efficiency of cleavage was more than 20 times greater in an argon atmosphere than in an oxygen atmosphere. The quantum yield in an air atmosphere was 1.7 (± 0.3) × 10 ‐8 . Sodium azide quenched the cleavage more efficiently in an oxygen atmosphere than when the oxygen concentration was reduced. Isopropanol and mannitol were poor quenchers; ribose‐5‐phosphate and guanosine‐5'‐monophosphate did not quench the cleavage. Substituting D 2 O for H 2 O increased the yield of SSBs in both oxygen and oxygen‐depleted atmospheres. The results are consistent with initiation of cleavage by reaction of the triplet state of rose bengal (or a radical derived from it) with DNA. In the presence of oxygen, an additional mechanism is introduced.