THE EFFECT OF MERCURIC IONS ON THE EXCITED STATES OF DNA-INTERCALATED ETHIDIUM BROMIDE |
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| Authors: | Stephen J Atherton Paul C Beaumont |
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| Institution: | Center for Fast Kinetics Research, ENS Annex 16N, University of Texas at Austin, Austin, TX 78712, USA;Faculty of Science, Health and Medical Studies, North East Wales Institute, Deeside, Clwyd CH5 4BR, UK |
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| Abstract: | 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 1.50.2103 m2 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 3.5103 s?1. An upper limit for the rate of detachment of Hg2+ from its binding site in DNA may be fixed at ca 103 s?1. |
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