A NOVEL FLUORESCENT TAG FOR LABELING OF SOME ANTISENSE OLIGONUCLEOTIDES

A new versatile fluorescent tag, 4-acetylamino-1,8-naphthalimido-N-cap roic acid (NCA) has been synthesized and characterized, and the optima l conditions for the maximum fluorescence using this tag allow a sensi tivity level of 10(-9) mol/1. Useful fluorescence is observed upon cov alent linking of this tag via its activated carboxy end to an alkylami no moiety, activated by the use of carbonyldiimidazole and hexamethyle nediamine at the 5'-termini of an octamer, d(TCTTGCTC), a 33-mer, and a 41-mer complementary to the tar initiator of the HIV-1 genome. A new method for the generation of alkylamino function at the 5'-termini of oligonucleotides by the use of N-(4-bromobutyl) phthalimide is also d escribed. The variation in fluorescence with respect to alteration of chain length of the oligonucleotides has also been studied. The fluore scence exhibited by these oligodeoxynucleotide (ODN)-NCA conjugates su ggests that they may have a potential application as experimental tool s in medicine and molecular biology. (C) 1997 Elsevier Science Ltd.