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DNA binding and intercalation by novel porphyrins: role of charge and substituents probed by DNase I footprinting and topoisomerase I unwinding
Author(s) -
Kuroda Reiko,
Takahashi Eitaro,
Austin Caroline A.,
Fisher L.Mark
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80213-3
Subject(s) - intercalation (chemistry) , porphyrin , footprinting , dna , chemistry , topoisomerase , stereochemistry , dna footprinting , crystallography , biophysics , photochemistry , biochemistry , biology , dna binding protein , inorganic chemistry , transcription factor , base sequence , gene
Porphyrins carrying four charged sidechains, e.g., meso ‐tetrakis[4‐ N ‐methylpyridiniumyl]‐ and meso ‐tetrakis[4‐ N ‐(2‐hydroxyethyl)pyridiniumyl]‐porphyrin, bound and intercalated similarly into DNA as measured by helix stabilization and DNA unwinding studies in the presence of DNA topoisomerase I. Despite their different bulky sidechains, these complexes gave essentially identical DNase I footprinting patterns. In contrast, tetrasubstituted porphyrins carrying three phenyl rings and a single positively charged pyridiniumyl sidechain did not intercalate and exhibited little affinity for DNA. Thus, the presence of charged sidechains on the porphyrin rather than their identity appears to be critical for efficient DNA intercalation. The results are discussed in regard to current models for the porphyrin‐DNA intercalation complex.