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Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
Exploring the mechanism of electron transfer between DNA and a ternary copper complex
Debarati Dey1, Nikhil R Pramanik, Samita Basu
1Department of Chemistry & Environment, Heritage Institute of Technology, Kolkata, India.
Abstract:
Photoinduced intramolecular electron transfer occurs in the triplet state within the complex [Htyr-Cu-phen](+) (Htyr = l-tyrosinato; phen = 1,10-phenanthroline) from tyrosine to phenanthroline. For this linked donor-acceptor system, a prominent magnetic field effect (MFE) is observed for the triplet-born radicals. The competitive binding study in the presence of ethidium bromide suggests that the complex interacts with calf thymus DNA (CT DNA) through partial intercalation. The photoexcited copper complex can oxidize DNA in a deoxygenated environment. Though the oxidation of tyrosine is thermodynamically more favorable than the oxidation of guanine, the primary electron transfer occurs from the DNA base to the phen ligand. A prominent MFE is observed for this noncovalently bound triplet-born guanine radical and phen radical anion. The process of partial intercalation of the copper complex within DNA is responsible for this rare observation.
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