Radiation chemical study of OH, O and SO4 - reactions with purines

Vinchukar, M. S. ; Rao, B. S. M. ; Mohan, H. ; Mittal, J. P. (1999) Radiation chemical study of OH, O and SO4 - reactions with purines Research on Chemical Intermediates, 25 (5). pp. 471-482. ISSN 0922-6168

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Official URL: http://www.ingentaconnect.com/content/vsp/rci/1999...

Related URL: http://dx.doi.org/10.1163/156856799X00068

Abstract

The reactions of 'OH, O.- and SO4.- with purine, adenine, adenosine and guanosine were studied by pulse radiolysis with optical detection. The second order rate constants for both O.- and SO4.- with these compounds range from (0.25 - 4.2) × 109 dm3 mol-1 s-1 and the k values for the O.- reaction are lower by an order of magnitude than those obtained for the corresponding 'OH reaction except in the case of purine where the rates are nearly the same. The transient absorption spectra measured in the reaction of .OH with purine, adenine and adenosine have characteristic peaks at 335 and 450 nm while absorption only in the lower wavelength region with peaks at 300 and 335 nm was observed in the O.- reaction. The rate of ring opening of the (C-8-O).- adduct of adenine is lower than that found for the 'OH reaction with practically no ring opening in the case of purine. In contrast, a single peak at 300 nm was observed in the O.- reaction with the nucleosides adenosine and guanosine. The spectral nature and the product analysis confirm that the H-abstraction by the O.- from the sugar moiety leading to the base release is an important reaction channel. The transient absorption spectra obtained in the SO4.- reaction with adenine and adenosine showed maxima at 290 and 335 nm with weak and broad absorption around 580 nm which are assigned to the neutral nitrogen centered radical.

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Deposited On:28 Feb 2012 11:57
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