2.1 Chemicals and Reagents
NaCl, Tris, and HCl were of analytical grade and purchased from Sinopharm Chemical Reagent Co. LTD (Beijing, China). ATP, ADP, AMP and lipoic acid were purchased from Sigma-Aldrich (Shanghai, China). The bicinchoninic acid (BCA) Protein Assay Kit was purchased from Beijing Solarbio Science & Technology Co. LTD (Beijing, China). Acetonitrile and trifluoroacetic acid (TFA) were of chromatographic grade and purchased from J&K Scientific Ltd. (Beijing, China). Chemically competent cells of E. coli TOP10 and E. coli BL21(DE3) were purchased from Weidishengwu Ltd. (Beijing, China). In-fusion cloning was used for the ligation of sequence fragments to vector with the In-fusion HD Cloning Kit (Clontech Laboratories, Inc, US). Luria-Bertani (LB) liquid medium (tryptone 10 g/L, yeast extract 5 g/L and NaCl 10 g/L) and solid medium (1.5% agar) with kanamycin (100 μg/mL), ampicillin (100 μg/mL) were used for transformation, screening, and cell growth.