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THE EFFECT OF MERCURIC IONS ON THE EXCITED STATES OF DNA‐INTERCALATED ETHIDIUM BROMIDE
Author(s) -
Atherton Stephen J.,
Beaumont Paul C.
Publication year - 1993
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.1751-1097.1993.tb02319.x
Subject(s) - ethidium bromide , excited state , quantum yield , chemistry , singlet state , triplet state , bromide , ion , photochemistry , intercalation (chemistry) , yield (engineering) , dna , atomic physics , fluorescence , inorganic chemistry , materials science , physics , organic chemistry , optics , biochemistry , metallurgy
The first excited triplet state of DNA‐intercalated ethidium bromide is produced with a quantum yield of 0.010.002 on irradiation at 532 nm. A difference extinction coefficient of 1.50.210 3 m 2 mol −1 is measured for the triplet state at 380 nm. Mercuric ions quench the first excited singlet state of DNA‐intercalated ethidium bromide via induced spin orbit coupling to give an increased yield of ethidium triplet states. The same mercuric ion that quenches the singlet state then quenches the triplet state, via the same mechanism, with a rate constant of ca 3.510 3 s −1 . An upper limit for the rate of detachment of Hg 2+ from its binding site in DNA may be fixed at ca 10 3 s −1 .