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Using Metal Complex Reduced States to Monitor the Oxidation of DNA

Olmon, Eric D. and Hill, Michael G. and Barton, Jacqueline K. (2011) Using Metal Complex Reduced States to Monitor the Oxidation of DNA. Inorganic Chemistry, 50 (23). pp. 12034-12044. ISSN 0020-1669. PMCID PMC3277451. doi:10.1021/ic201511y.

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Metallointercalating photooxidants interact intimately with the base stack of double-stranded DNA and exhibit rich photophysical and electrochemical properties, making them ideal probes for the study of DNA-mediated charge transport (CT). The complexes [Rh(phi)_2(bpy′)]^(3+) (phi = 9,10-phenanthrenequinone diimine; bpy′ = 4-methyl-4′-(butyric acid)-2,2′-bipyridine), [Ir(ppy)_2(dppz′)]^+ (ppy = 2-phenylpyridine; dppz′ = 6-(dipyrido[3,2-a:2′,3′-c]phenazin-11-yl)hex-5-ynoic acid), and [Re(CO)_3(dppz)(py′)]^+ (dppz = dipyrido[2,3-a:2′,3′-c]phenazine; py′ = 3-(pyridin-4-yl)-propanoic acid) were each covalently tethered to DNA to compare their photooxidation efficiencies. Biochemical studies show that upon irradiation, the three complexes oxidize guanine by long-range DNA-mediated CT with the efficiency: Rh > Re > Ir. Comparison of spectra obtained by spectroelectrochemistry after bulk reduction of the free metal complexes with those obtained by transient absorption (TA) spectroscopy of the conjugates suggests that the reduced metal states form following excitation of the conjugates at 355 nm. Electrochemical experiments and kinetic analysis of the TA decays indicate that the thermodynamic driving force for CT, variations in the efficiency of back electron transfer, and coupling to DNA are the primary factors responsible for the trend observed in the guanine oxidation yields of the three complexes.

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Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2011 American Chemical Society. Received: July 15, 2011. Publication Date (Web): November 1, 2011. We are grateful to the NIH (GM49216) for financial support. E.D.O. also thanks E.D.A. Stemp, J.R. Winkler, and B. Elias for technical assistance and fruitful discussions.
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Issue or Number:23
PubMed Central ID:PMC3277451
Record Number:CaltechAUTHORS:20120113-114638971
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Official Citation:Using Metal Complex Reduced States to Monitor the Oxidation of DNA Eric D. Olmon, Michael G. Hill, and Jacqueline K. Barton Inorganic Chemistry 2011 50 (23), 12034-12044
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28785
Deposited By: Ruth Sustaita
Deposited On:13 Jan 2012 21:04
Last Modified:09 Nov 2021 17:00

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