Isopropyl β d thiogalactopyranoside

Yeast extract and tryptone were purchased from Oxoid (Shanghai, China). Pyridoxal-5’-phosphate (PLP), pyruvate and R-1-phenylethylamine (1-(R)-PEA) were purchased from Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Choline chloride (ChCl), urea, ethylene glycol (EG), propylene glycol (PG), glycerol, formate, kanamycin sulphate, isopropyl–β-d-thiogalactopyranoside (IPTG), sodium dihydrogen phosphate, disodium phosphate, imidazole, sodium chloride, Ni-NTA Sefinose™ Resin (Settled Resin), Modified Bradford Protein Assay kit and SDS PAGE gel kit were obtained from Sangon (Shanghai, China). Amicon^®® Ultra Filter units were obtained from Sigma Aldrich (Shanghai, China). All chemicals were of analytical grade. The transaminase genes from Aspergillus terreus, which were previously transformed in E. coli BL21 (DE3) pRSF-D-AAO competent cells, were stored in our laboratory at −80 °C. The plasmids and the E. coli BL21 (DE3) pRSF-D-AAO competent cells were constructed by Anhui General Biology Company (Anhui, China).

Ampicillin, β-mercaptoethanol, imidazole, and isopropyl-β-D-thiogalactopyranoside (IPTG) were purchased from Sangon Biotech (Shanghai, China). Tryptone and yeast extract were obtained from Oxoid (Basingstoke, Hampshire, UK). Ni-NTA agarose (catalog no. 30230) and rhodamine B (catalog no. 83689) were obtained from Qiagen (Hilden, Germany) and Sigma (St. Louis, MO, USA), respectively. Coomassie Brilliant Blue R-250 (catalog no. 161-0400) was purchased from Bio-Rad (Hercules, CA, USA). All other chemicals were of the highest purity available from commercial suppliers.
PrimeSTAR Max DNA polymerase for polymerase chain reaction (PCR) was obtained from Takara Biotechnology Co., Ltd. (Dalian, China). Restriction enzymes and T4 DNA ligase were obtained from New England Biolabs (Ipswich, MA, USA). TIANprep Mini Plasmid Kit, TIANgel Midi Purification Kit, and chemically competent cells of E. coli DH5α and BL21(DE3) were purchased from Tiangen Biotech Co., Ltd. (Beijing, China). Amicon Ultra-15 centrifugal filter units with Ultracel-3K membranes (3 kDa molecular weight cutoff) were obtained from Millipore (Billerica, MA, USA), and a Pierce BCA Protein Assay Kit (catalog no. 23225) was purchased from Thermo Fisher Scientific Inc. (Rockford, IL, USA).

Lysogeny broth (LB) medium (g L⁻¹) was composed as follows: peptone 10.0 g L⁻¹, yeast extract 5.0 g L⁻¹, NaCl 10.0 g L⁻¹, pH 7.2, (solid, addition of 1.5% agar), and deionized water 1000 mL, which was sterilized at 121 °C for 20 min.
Proteinase K, lysozyme, ampicillin (Amp), kanamycin (Km), gentamicin (Gm), isopropyl-β-D-thiogalactopyranoside (IPTG), o-nitrophenyl β-D-galactopyranoside (ONPG), and o-nitrophenol (ONP) were purchased from Shanghai Sangon Biotech (Sangon Biotech, Shanghai, China). GA C15:1 standard was purchased from Shanghai Tauto Biotechnology (Shanghai, China). Other chemical reagents were analytical grade.