title: Spectrophotometric analysis of nucleic acids: oxygenation-dependent hyperchromism of DNA.
abstract: The absorbance at 260 nm (A(260)) is ubiquitously used for nucleic acid quantification. We show that following oxygenation, DNA solutions experience alterations in both spectral properties (hyperchromism in the UV region, lambda(max) 260 nm) and DNA conformation. The spectral changes caused by oxygen-DNA complexation are stable for at least several weeks at room temperature or several hours at 37 degrees C, but are also reversible by purging with nitrogen. Our data indicate that DNA in working solutions might already exist in the oxygen-complexed state, potentially confounding spectrophotometric analyses. Further, the presence of these complexes does not appear to impart cell toxicity in vitro or affect the biophysical functional behaviour (e.g. hybridisation) of DNA. Interestingly, our work also suggests that hybridisation could determine a release of bound oxygen, a phenomenon that could open the way to the use of such systems as oxygen carriers.
authors.affiliation: School of Translational Medicine, Manchester Interdisciplinary Biocentre, The University of Manchester, Manchester M1 7ND, UK. rd368@cam.ac.uk
authors.forename: Rupak
authors.initials: R
authors.lastname: Doshi
authors.forename: Philip J R
authors.initials: PJ
authors.lastname: Day
authors.forename: Paolo
authors.initials: P
authors.lastname: Carampin
authors.forename: Ewan
authors.initials: E
authors.lastname: Blanch
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Stratford
authors.forename: Nicola
authors.initials: N
authors.lastname: Tirelli
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D004247:DNA / Q000737:chemistry*; D051379:Mice; D009690:Nucleic Acid Conformation; D010100:Oxygen / Q000737:chemistry*; D012474:Salmon; D013053:Spectrophotometry / Q000379:methods*
chemical_list: D004247:DNA; D010100:Oxygen