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

Abstract

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 beta-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.

Oriented Immobilization of Proteins on Hydroxyapatite Surface Using Bifunctional Bisphosphonates as Linkers

“…The enhanced affinity of HBPs was measured using a crystal growth inhibition study. , HBPs have a hydrazine on their R 2 substituent that is linked with various length and lipophilicity spacer arms to the BP group. Hydrazine reacts with aldehyde at low pH (4.5 to 7.4), − where the lysine amine groups of the protein are protonated, rendering them unreactive. Moreover, hydrazines react faster than amines to aldehydes and ketones, and reaction of hydrazines with aldehydes results in the formation of a stable hydrazone bond.…”

Modified Nucleotides as Substrates of Terminal Deoxynucleotidyl Transferase

“…Recently, much attention has been paid to the preparation of hydrazine functionality-containing nucleotides and ONs [ 48 , 49 , 50 , 51 , 52 , 53 ]. It has been shown that N 4 -aminocytidine induces an AT to GC transition and can function as a mutagen [ 54 ].…”

“…Compared to well-known amino-modified ONs, hydrazines exhibit enhanced reactivity with active esters at neutral to acidic conditions as well as generate more stable adducts—hydrazones—reacting with aldehydes [ 50 ]. Usually, the hydrazine group is introduced into ON post-synthetically [ 48 , 49 , 52 , 53 ] and only recently the protected hydrazine amidites have been reported [ 50 , 51 ]. Both conjugation and immobilization of ONs continue to develop towards high-throughput technologies, therefore significance of hydrazine-modification is obvious.…”