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Privat, E ; Melvin, T ; Merola, F ; Schweizer, G ; Prodhomme, S ; Asseline, U ; Vigny, P

Fluorescent properties of oligonucleotide-conjugated thiazole orange probes

Photochemistry and Photobiology 75 (3) 201-210

par Administrateur - publié le

Abstract :

The fluorescence properties of thiazole orange, linked via a (1) hydrophobic alkyl or a (2) hydrophillic ethylene glycol chain to the central internucleotidic phosphate group of a pentadeca-2’-deoxyriboadenylate (dA(15)), are evaluated. Linkage at the phosphate group yields two stereoisomers, S-isomer of the phosphorus chiral center (Sp) and R-isomer of the phosphorus chiral center (Rp) ; these are studied separately. The character of the linkage chain and the chirality of the internucleotidic phosphate linkage site influence the fluorescent properties of these thiazole orange-oligonucleotide conjugates (TO-probes). Quantum yields of fluorescence (Phi(fl)) of between 0.04 and 0.07 were determined for the single-stranded conjugates. The fluorescence yield increased by up to five times upon hybridization with the complementary sequence (d5’[CACT(15)CAC(3’)]) ; Phi(fl) values of between 0.06-0.35 were determined for the double-stranded conjugates. The Phi(fl) value (0.17) of thiazole orange, 1-(N,N’-trimethylaminopropyl)-4-[3-methyl-2,3-dihydro-(benzo-1,3-thiazole)- 2-methylidene]-quinolinium iodide (TO-Pro 1) in the presence of the oligonucleotide duplex (TO-Pro 1 : dA(15)(.)d(5’)[CACT(15)CAC(3’)] (1:1)) is much less than that for some of the hybrids of the conjugates.