Enzymatic Synthesis of 5-Aza-2’-Deoxycytidine

The enzyme (N-deoxyribosyltransferase-II) gene (ntd) in Lactobacillus helveticus was cloned into E.coli BL21（DE3）to recombine a prokaryotic expression bacteria PND. The bacteria PND expressed large amounts of N-deoxyribosyltransfer ase-II with IPTG as an inducement. The 5-aza-2’-deoxycytidine and thymine were synthesied at the substrate of 5-azacytosine and deoxythymidine by the enzyme of N-deoxyribosyltrans-ferase-Ⅱ. The optimum condition was 2 mmol/L of subtrates, 20 mmol/L of Tris-HCl (pH 7.1), 200 μL of enzyme, 2 mL of reaction volume, and 2 h of reaction time at 55 ℃. Conversion of substrate reached 61% at the optimum condition.