Quenching of nucleotide-derived radicals by bisbenzimidazole derivative Hoechst-33258 in aqueous solution

Mohan, H and Adhikary, A and Jain, V and Mittal, JP (2000) Quenching of nucleotide-derived radicals by bisbenzimidazole derivative Hoechst-33258 in aqueous solution. In: Proceedings of the Indian Academy of Sciences Chemical Sciences, 112 (4). pp. 487-496.

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Abstract

The pulse radiolysis technique has been employed to investigate the reaction of DNA-minor-groove ligand bisbenzimidazole Hoechst 33258 with pyrimidine and purine nucleotide-derived radicals. Formation of an N-centred Hoechst-33258 radical is observed. Bimolecular rate constants and the yields of Hoechst-33258 radical have been evaluated. While the rate constant for the reaction of pyrimidine-derived radicals with Hoechst-33258 remained the same (1–2) *109 dm3 mol–1 s–1, the yields of the Hoechst-33258 radical varied from 25% (5’-cytidine monophosphate) to 75% (5’-guanosine monophosphate) under anoxic conditions. The rate constant values for the reaction of purine-derived radicals with Hoechst-33258, under oxic and anoxic conditions, remained the same whereas with pyrimidine-derived radicals, the rate constant value under anoxic conditions was about two orders of magnitude lower than under anoxic conditions. The difference in the yields of Hoechst-33258 radical with various nucleotide-derived radicals suggest the formation of different types of radicals and that the reaction mainly occurs by electron transfer from Hoechst-33258 to the nucleotide radicals.

Item Type:	Journal Article
Publication:	Proceedings of the Indian Academy of Sciences Chemical Sciences
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Keywords:	Nucleotide-derived radicals;Hoechst-33258;pulse radiolysis
Department/Centre:	Division of Physical & Mathematical Sciences > Mathematics
Date Deposited:	04 Oct 2004
Last Modified:	29 Feb 2012 06:31
URI:	http://eprints.iisc.ac.in/id/eprint/1679

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