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Photoinduced electron transfer quenching of excited Ru(II) polypyridyls bound to DNA: the role of the nucleic acid double helix

Orellana, Guillermo and Kirsch-De Mesmaeker, Andree and Barton, Jacqueline K. and Turro, Nicholas J. (1991) Photoinduced electron transfer quenching of excited Ru(II) polypyridyls bound to DNA: the role of the nucleic acid double helix. Photochemistry and Photobiology, 54 (4). pp. 499-509. ISSN 0031-8655. doi:10.1111/j.1751-1097.1991.tb02049.x.

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In the presence of double helical polynucleotides (sodium poly(dA-dT)-poly(dA-dT) or calf thymus DNA), the efficiency of oxidative or reductive electron transfer between photoexcited ruthenium(II) chelates Ru(tap)2(hat)^(2+) or Ru(phen)^(⅔+) (where tap =1,4,5,8-tetraazaphenanthrene, hat = 1,4,5,8,9,12-hexaazatriphenylene, and phen = 1,10-phenanthroline) and appropriate cationic quenchers (ethidium, Ru(NH3)3/6^+, methyl viologen, or M(phen)3/3^+, where M = Co, Rh, Cr) increases 1–2 orders of magnitude compared to the efficiency of the same quenching in microhomogeneous aqueous medium (k_q= 0.3-1.8 × 10^9 M's^(−1)). The enhancement is more pronounced when the binding constant of the quencher (10^3 < Kh < 10^6 M^(−1)) is large. Similar trends are found when the biopolymers are replaced by sodium poly(styrenesulfonate) (PSS). The accelerated electron transfer process is proposed to be due mainly to the effect of accumulation of the reagents in the electrostatic field of the polymer; if corrections for this effect are introduced (e.g. ratioing [quencher]/[polynucleotide]), the reaction rate becomes essentially independent of the polymer concentration. Based upon a model for electron transfer reaction of the complexes within a small cylindrical interface around the DNA helix, calculations of the bimolecular electron transfer rate constants are computed to be 10′ times smaller when the reactants are bound to the double-stranded polynucleotides and decreased mobility of the cationic species is apparent. The effect is less pronounced if a simpler polyelectrolyte (PSS) is employed. Emission lifetimes of the Ru(II) polypyridyls bound to the DNA (0.32–2μs, double exponential decays) are discussed as well.

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Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 1991 Pergamon Press. (Received 16 January 1991; accepted 16 April 1991) The authors gratefully acknowledge the NATO for a Scientific Research Grant (A.K.-D.), and the Spanish Ministry of Education and Science and the U.S. Government for a Fulbright Postdoctoral Fellowship (G.O.) under which this work was performed. They are also grateful to Professor J. Nasielski, F. de Buyl, and L. Jacquet for their gift of Ru(tap)_2(hat^(+2), and thank the NIH (GM33309) for its generous support. Additional support from NSF and AFOSR is acknowledged.
Funding AgencyGrant Number
North Atlantic Treaty Organization (NATO)UNSPECIFIED
Ministerio de Educacion y Ciencia (MEC)UNSPECIFIED
Fulbright Scholar ProgramUNSPECIFIED
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Issue or Number:4
Record Number:CaltechAUTHORS:20160126-113442705
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Official Citation:Orellana, G., Mesmaeker, A. K.-D., Barton, J. K. and Turro, N. J. (1991), PHOTOINDUCED ELECTRON TRANSFER QUENCHING OF EXCITED Ru(II) POLYPYRIDYLS BOUND TO DNA: THE ROLE OF THE NUCLEIC ACID DOUBLE HELIX. Photochemistry and Photobiology, 54: 499–509. doi:10.1111/j.1751-1097.1991.tb02049.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63974
Deposited By: George Porter
Deposited On:26 Jan 2016 23:13
Last Modified:10 Nov 2021 23:23

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