Enzymatic synthesis of 2'-deoxyguanosine with nucleoside deoxyribosyltransferase-II.

Nucleoside deoxyribosyltransferase-II (NdRT-II) of Lactobacillus helveticus, which catalyzes the transfer of a glycosyl residue from a donor deoxyribonucleoside to an acceptor base, has a broad specificity for the acceptor bases. Six-substituted purines were found to be substrates as acceptor bases for NdRT-II. Using this property of the enzyme, we established a practical procedure for enzymatic synthesis of 2'-deoxyguanosine (dGuo), consisting of the transglycosylation from thymidine to 6-substituted purine (2-amino-6-chloropurine; ACP) instead of natural guanine and the conversion of 2-amino-6-chloropurine-2'-deoxyriboside (ACPdR) to dGuo with bacterial adenosine deaminase. Through the successive reactions, dGuo was synthesized in high yield.