Nucleic Acids Research, Vol 27, Issue 10 2219-2226, Copyright © 1999 by Oxford University Press
RN Bose, S Moghaddas, PA Mazzer, LP Dudones, L Joudah and D Stroup
Chromium(V)-mediated oxidative damage of deoxy-ribonucleic acids was
investigated at neutral pH in aqueous solution by utilizing bis(2-ethyl-
2-hydroxy-butanato)oxochromate(V) (I) and bis(hydroxyethyl)-amino-
tris(hydroxymethyl)methane)oxochromate(V) (II). Single-stranded and
double-stranded (ds) calf thymus and human placenta DNA, as well as two
oligomers, 5'-GATCTAGTAGGAGGACAAATAGTGTTTG-3' and 5'-
GATCCAAGCAAACACTATTTGTCCTCCTACTA-3', were reacted with the chromium(V)
complexes. Most products were separated and characterized by chroma-
tographic and spectroscopic methods. Polyacrylamide gel electrophoresis
experiments reveal more damage at G sites in comparison to other bases.
Three primary oxidation products, 5-methylene-2-furanone (5-MF), furfural
and 8-oxo-2'-deoxyguanosine, were characterized. A minor product, which
appears to be thymine propenal, was also observed. The dsDNA produces more
furfural than furanone. The formation of these two products resulted from
hydrogen ion or hydride transfer from C1' and C5' positions of the ribose
to the oxo-chromium(V) center. Since no enhancements of these products
(except propenal) were observed in the presence of oxygen, mechanisms
pertaining to the participation of activated oxygen species may be ruled
out. The oxidation of the G base is most likely associated with an oxygen
atom transfer from the oxo- metallates to the double bond between C8 and N7
of the purine ring. The formation of the propenal may be associated with an
oxygen-activated species, since a marginal enhancement of this product was
observed in the presence of oxygen. The formation of furfural in higher
abundance over 5-MF for dsDNA was attributed to the ease of hydrogen ion
(or hydride transfer) from the C5' compared to C1' position of the ribose
within a Cr(V)-DNA intermediate in which the metal center is bound to the
phosphate diester moiety.
ARTICLES
Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation
Department of Chemistry, Kent State University, Kent, OH 44242, USA. rbose@platinum.kent.edu
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