title: Kinetic model studies on the chemical ligation of oligonucleotides via hydrazone formation.
abstract: We report on the suitability of hydrazone formation for activator-free ligation of oligonucleotides. 5'-Acyl hydrazides were synthesized using a previously described phosphoramidite modifier, whereas 3'-hydrazides resulted from a hydrazinolysis of an ester group serving as a linker to the solid support. Aromatic aldehydes could be directly introduced on the 5'-terminus via the respective phosphoramidates. Aliphatic aldehydes were generated by periodate cleavage of the corresponding 3'- and 5'-modified diol precursors. Ligation of a 3'-hydrazide-modified oligonucleotide with oligonucleotides bearing an aromatic aldehyde in 5'-position showed a fast reaction kinetics (k(1) about 10(-1) M(-1)s(-1)) [corrected] and irreversible hydrazone formation. The ligation of a 5'-hydrazide-modified oligonucleotide and a 3'-ribobisaldehyde appeared to proceed reversibly at the beginning, but became irreversible with increasing reaction time. Hydrazide-modified oligonucleotides were found to be somewhat unstable in aqueous solutions.
authors.affiliation: Lehrstuhl für Organische Chemie I, Ruhr-Universität-Bochum, D-44780 Bochum, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Achilles
authors.forename: G V
authors.initials: GV
authors.lastname: Kiedrowski
mesh_terms: D020650:Combinatorial Chemistry Techniques; D006835:Hydrazones / Q000138:chemical synthesis*; D007700:Kinetics; D015335:Molecular Probes; D009841:Oligonucleotides / Q000737:chemistry*; D009943:Organophosphorus Compounds; D013329:Structure-Activity Relationship
chemical_list: D006835:Hydrazones; D015335:Molecular Probes; D009841:Oligonucleotides; D009943:Organophosphorus Compounds; C434331:phosphoramidite