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PROBING PHOTODYNAMIC DAMAGE IN NUCLEIC ACIDS WITH A DAMAGE‐SPECIFIC DNA BINDING PROTEIN: A COMPARISON OF THE B and Z DNA CONFORMATIONS
Author(s) -
Feldberg Ross S.,
Brown Caroline,
Carew Josephine A.,
Lucas Judith L.
Publication year - 1983
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.1751-1097.1983.tb04511.x
Subject(s) - guanine , singlet oxygen , nucleic acid , dna , chemistry , steric effects , dna damage , quenching (fluorescence) , reactivity (psychology) , stereochemistry , photochemistry , biochemistry , nucleotide , oxygen , organic chemistry , fluorescence , medicine , physics , alternative medicine , pathology , quantum mechanics , gene
—We have employed a damage‐specific DNA binding protein from human cells as a probe for base damage in polymers irradiated with white light in the presence of methylene blue. Protein‐recognizable damage is introduced only into guanine‐containing polymers and quenching of damage introduction by H 2 O and sodium azide suggest the involvement of a singlet oxygen mechanism. Using poly d(G‐m 5 C), we have demonstrated that the left‐handed double helical Z conformation is much less susceptible to guanine photooxidation than is the usual B conformation. We speculate that this difference in reactivity may reflect steric hindrance at the purine C‐4 position and could provide some insight into the initial steps of the reaction between singlet oxygen and guanine in nucleic acid polymers.