Synthesis of oligonucleotides containing the alkali-labile pyrimidopurinone adduct, M(1)G

An improved method for the synthesis of oligodeoxyribonucleotides containin g the endogenous adduct, pyrimido [1,2-a]purin-10(3H)-one (M(1)G), is repor ted. The key features of the methodology include improved synthesis of the deoxynucleoside of M(1)G by transribosylation with deoxycytidine catalyzed by nucleoside 2'-deoxyribosyltransferase and the use of commercially availa ble 4-tert-butylphenoxyacetyl protecting groups for normal nucleotides. Fac ile deprotection and removal of the M(1)G-containing oligomers from the sol id support were achieved by treatment with a solution of potassium carbonat e in methanol. NMR studies were performed to determine the stability of the oligonucleotides at different pHs.