Preactivated carboxyl linker for the rapid conjugation of alkylamines to oligonucleotides on solid support.

A C10 linker phosphoramidite reagent terminated with a succinimidyl-activated carboxyl group was prepared and used to couple to the 5'-end of an oligonucleotide synthesized on a solid support. The succinimidyl-activated carboxyl functionality can be used for rapid conjugation of amines to oligonucleotides on solid support or it can be hydrolyzed to form a carboxylic acid functionality. The activated linker was successfully used for conjugation of several primary and secondary aliphatic amine derivatives (including biotin and fluorescein cadaverine) onto a solid support-bound 12-mer DNA oligonucleotide at scales ranging from 0.15 to 1.0 micromol. The overall yields of the conjugation products after AMA deprotection and cleavage from the solid support ranged from 43 to 75% of the total oligonucleotide product. This value is significant, as it includes oligonucleotide synthesis, coupling of the linker, and conjugation of the amine. In addition, the entire process of oligonucleotide synthesis, linker coupling, amine conjugation, deprotection, and cleavage of the oligonucleotide from solid support can be accomplished in 1 day.