Efficient synthesis of (3R,5S)-6-chloro-2,4,6-trideoxyhexapyranose by using new 2-deoxy-D-ribose-5-phosphate aldolase from Streptococcus suis with moderate activity and aldehyde tolerance

The enzyme 2-deoxy-D-ribose-5-phosphate aldolase (DERA) is a useful tool for synthesizing statin side-chain intermediates. In this work, we identified the DERA from Streptococcus suis (SsDERA) by structural and sequence alignment and highly expressed it in Escherichia coli BL21. The recombinant SsDERA had a specific activity of 18.2 U mg(-1), K-M of 0.8 mM, and V-max of 32.9 mu mol min(-1) mg(-1) toward 2-deoxy-D-ribose-5-phosphate under the optimal conditions: 40 degrees C and pH 7.0. The enzyme retained 23.3 % activity after incubation in 200 mM acetaldehyde for 2 h and 58.2 % activity in 100 mM chloroacetaldehyde for 2 h. The enzyme showed moderate activity and aldehyde tolerance compared with reported DERAs. The SsDERA-catalyzed reaction between 200 mM acetaldehyde and 100 mM chloroacetaldehyde generated (3R,55)-6-chloro-2,4,6-trideoxyhexapyranose in 76 % yield in 8 h. This work provides a new DERA for the synthesis of (3R,55)-6-chloro-2,4,6-trideoxyhexapyranose, which is a potential candidate for the industrial synthesis of statin intermediates.