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COMPLEX FORMATION BETWEEN ETHIDIUM BROMIDE AND THE NUCLEOTIDES AMP AND GMP
Author(s) -
Maniooth D.,
Georghiou S.
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.tb03393.x
Subject(s) - ethidium bromide , nucleotide , chemistry , fluorescence , molecule , bromide , dna , purine metabolism , stereochemistry , enzyme , biochemistry , inorganic chemistry , organic chemistry , physics , quantum mechanics , gene
— The antimicrobial drug ethidium bromide (EB) has been found to form molecular complexes with nucleotides, the strongest being those with the purines AMP and GMP. For the EB‐AMP and EB‐GMP complexes (which we characterized) the values of the ground‐state association constant have been found to be 100 and 103 M ‐1 , respectively. The fluorescence of the drug is enhanced when complexed to AMP, GMP, and TMP by about 60, 30 and 10%, respectively, whereas it is quenched by about 20% when complexed to CMP. Fluorescence enhancement analysis has yielded the values of 1.1 × 10 10 and 0.7 × 10 10 M ‐1 s ‐1 for the excited‐state rate constant of complex formation with the former two nucleotides, respectively. About one out of two collisions between an excited EB molecule and an AMP or GMP molecule results in complex formation. The potential implications of these findings for the EB‐DNA interaction are discussed.