Enzymatic synthesis of 2′-O-methylribonucleosides with a nucleoside hydrolase family enzyme from Lactobacillus buchneri LBK78

2′-O-Methylribonucleosides (2′-OMe-NRs) are promising raw materials for the production of nucleic acid drugs. We previously reported that LbNH, a nucleoside hydrolase from Lactobacillus buchneri LBK78 (NITE P-01581), was the first enzyme found to act on 2′-OMe-NRs. In the present study, we determined that LbNH also has the transribosylation activity between 2′-OMe-NRs and nucleobases, in addition to the hydrolyzing activity towards 2′-OMe-NRs. When 2′-O-methyluridine (2′-OMe-UR) and adenine were reacted with LbNH, 2′-O-methyladenosine (2′-OMe-AR) was produced. LbNH preferred purine nucleobases as its acceptor substrates for the transribosylation with 2′-OMe-UR as a donor substrate. Kinetic analysis of LbNH revealed that adenine behaved as a mixed inhibitor of the hydrolysis of 2′-OMe-UR. Under the optimal reaction conditions, the maximum molar yield of enzymatic 2′-OMe-AR produced reached 0.97% towards 2′-OMe-UR, corresponding to 0.16 g/L.