S.I. Antsypovich

Synthesis of Modified Oligonucleotides and Production of Duplexes With Covalently Linked Chains

Abstract A method has been devised to synthesize a DNA-duplex with covalently connected strands. Primary amino group located on one strand is linked to a carboxyl group of the other strand through the agency of a water soluble carbodiimide condensing agent. Conditions for the reaction between chains of a duplex composed of the modified oligonucleotides [1] were optimized. The thermal and hydrolytic stability of the cross linked duplex was examined.

A Novel Versatile Phosphoramidite Building Block for the Synthesis of 5′- and 3′-Hydrazide Modified Oligonucleotides

We introduce a novel versatile phosphoramidite building block for the modification of oligonucleotides (ONs) with acyl hydrazides on the 5′- or 3′-terminus, or both. The reaction of these hydrazide functionalized ONs with 4-methoxyphenylaldehyde is demonstrated for solution derivatization. Hydrazides are considered nowadays as promising reactants, which show enhanced reactivity at neutral and slightly acidic conditions and higher stability of yielding products as compared to the aliphatic amines, which are broadly used for ONs derivatization. Our method to introduce hydrazides into ONs employs a phosphoramidite modifier designed to split, during ammonia or lithium hydroxide treatment, into two hydrazides via β-elimination of a central bis-2-carbonylethoxysulfone unit. It allows the creation of ONs derivatized with a hydrazide moiety at the 5′-, 3′- and both 5′- and 3′-termini, as well as two different hydrazide containing ONs at the same time, viz. in one sequence on the same solid support. In latter case one can, for example, synthesize two hydrazide containing ONs, where one is 5′-modified and second one is 3′-modified. This work was supported by German Research Council (DFG) and the Federal Ministry of Education and Research (BMBF, Germany). S.I. Antsypovich gratefully acknowledges a stipend and his fellowship from German Academic Exchange Service (DAAD) and Alexander von Humboldt Foundation (AvH-Stiftung, Germany), respectively.

Synthesis and properties of modified oligodeoxyribonucleotides containing 9-(2-amino-2-deoxy-beta-D-arabinofuranosyl)adenine

Abstract The synthesis of modified oligodeoxyribonucleotides# containing 2′-amino-2′-deoxyarabinoadenosine residues (aAn) was carried out by means of the standard phosphoramidite chemistry. A high reactivity of such compounds to electrophilic reagents was shown. The cross-link formation between 2′-amino group of aAn and carboxyl function introduced into complementary strands occurs with 55% yield. The aAn residues was shown to induce the increased resistance of modified oligomers towards the enzymatic cleavage and provide the insignificant destabilization of DNA duplexes. This publication is dedicated to Professor Tsujiaki Hata, who made a valuable contribution to the chemistry of nucleosides and nucleotides.

New phosphoramidite derivatives for the preparation of oligonucleotides containing a hydrazide group in any specified position of the oligonucleotide chain

A new versatile method for the preparation of oligonucleotides containing hydrazide groups in any position of the oligonucleotide chain by standard phosphoramidite automated oligonucleotide synthesis is proposed. The method is based on the use of a series of new modified components for oligonucleotide synthesis. An original protecting group for the hydrazide group is proposed. The presence of the hydrazide group in the obtained oligonucleotides and its high reactivity were demonstrated by the reaction with 4-methoxybenzaldehyde in solution.

Synthesis and properties of cross-linked DNA duplexes

A method has been devised to synthesize DNA duplexes with covalently connected strands. The structure of cross‐linked duplexes was confirmed by a reaction with the restriction endonuclease AluI. The thermal stability of the resulting compounds was investigated.