Inhibition of peroxyoxalate chemiluminescence by intercalation of fluorescent acceptors between DNA bases

• Published in: Photochemistry and photobiology 1999-04, Vol.69 (4), p.405-409
• Main Authors: Alba, F J, Daban, J R
• Format: Article
• Language: English
• Subjects: Animals; Cattle; DNA - chemistry; DNA - drug effects; DNA - radiation effects; Fluorescent Dyes; In Vitro Techniques; Intercalating Agents; Luminescent Measurements; Oxalates; Photochemistry
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1562/0031-8655(1999)069<0405:IOPCBI>2.3.CO;2

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.