2.1 Reagents and enzymes
Sucrose, isomaltulose, HPLC-grade acetonitrile were bought from Aladdin (Shanghai, China). PrimSTAR Max DNA Polymerase, restriction enzymes, protein markers and Dpn I were obtained from TaKaRa (Dalian, China). Plasmid Mini Preparation Kit and BCA Protein Assay Kit were provided by Beyotime (Shanghai, China). Isopropyl-β-D-thiogalactopyranoside (IPTG) and chloramphenicol was supplied by Yuanye Bio-Technology (Shanghai, China). All other reagents were purchased from Sinopharm Chemical Reagent (Shanghai, China) unless otherwise noted.