title: Inhibition of peroxyoxalate chemiluminescence by intercalation of fluorescent acceptors between DNA bases.
abstract: We have examined the ability of different fluorescent DNA dyes to become chemically excited by the peroxyoxalate chemiluminescent reaction. The intercalating dyes ethidium bromide and propidium iodide, and the bis-intercalating dyes ethidium homodimer-1, benzoxazolium-4-pyridinium dimer-1 and benzoxazolium-4-quinolinium dimer-1, exhibit an intense chemiluminescence when they are excited by the bis(2,4,6-trichlorophenyl)oxalate (TCPO)-H2O2 reaction in the absence of DNA. However, the chemiluminescence of these dyes is very low when they are bound to double-stranded DNA (dsDNA). In contrast, the minor groove-binding dye Hoechst 33258 excited by the TCPO-H2O2 reaction shows approximately the same chemiluminescence intensity when it is free in solution or complexed with dsDNA. Structural alterations or partial dissociation of dsDNA-bis-intercalating dye complexes produced by the addition of acetone, NaCl, MgCl2 or the cationic surfactant cetyltrimethylammonium bromide increases the chemiluminescence intensity. A moderate chemiluminescence intensity is observed when bis-intercalating dyes are complexed with single-stranded DNA. Our results indicate that the energy from the intermediates produced in the peroxyoxalate chemiluminescent reaction cannot be efficiently transferred to fluorescent dyes complexed with DNA; chemiexcitation is almost completely inhibited when dyes are buried in the dsDNA structure by intercalation between the base pairs.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Alba
authors.forename: J R
authors.initials: JR
authors.lastname: Daban
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000187:drug effects* / Q000528:radiation effects; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007364:Intercalating Agents; D008163:Luminescent Measurements; D010070:Oxalates; D010777:Photochemistry
chemical_list: D005456:Fluorescent Dyes; D007364:Intercalating Agents; D010070:Oxalates; C044622:peroxyoxalate; D004247:DNA