Protein marker

The crocodile (Crocodylus siamensis) meat was purchased from the Huarun supermarket, Guangzhou, China. The meat was brought in an ice box to the laboratory and refrigerated at − 20 °C before use. The silica gel and silica gel G plates (thickness 0.25 mm, 100 × 100 mm or 200 × 100 mm) were purchased from Qingdao Marine Chemicals Co. (Qingdao, China). Protein marker is purchased from Takara Co. (Shanghai, China). Coomassie brilliant blue R-250 and G250, DPPH (diphenyl picryl hydrazinyl radical), ABTS [2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate)], and BCA (bicinchoninic acid) were purchased from Qihuashen Co. (Guangzhou, China). Papain (2.0 × 10⁵ U/g), pepsin (2.3 × 10⁵ U/g), trypsin (1.5 × 10⁵ U/g) and alcalase (3.0 × 10⁵ U/g) were purchased from Qihuashen Co. (Guangzhou, China). Other chemical and biochemical reagents are analytical or biochemical grade and were purchased from local suppliers.

Diammonium 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic sulfonate, ABTS), acid violet, alphazurine A, and methyl orange were purchased from Sigma-Aldrich (St. Louis, MO, USA). Restriction enzymes EcoR I, Kpn I, Prime STAR Max, DNA Marker, and Protein Marker all purchased from TaKaRa (Dalian China). The bacterial genomic DNA extraction kit, instant error-prone PCR kit, agarose gel DNA recovery kit, plasmid extraction kit, and fast site-directed mutagenesis kit all purchased from TianGen (Beijing, China). Ampicillin, kanamycin, and IPTG were purchased from Solarbio (Beijing, China). His-tagged protein purification kit was purchased from Kangweishiji (Beijing, China). All other chemicals were standard reagent grade.
PCR instrument (T100™ Thermal Cycler, Bio-Rad) Molecular Devices Spectra Max M2 microplate reader, Ultrasonic processor type ultrasonic crusher, E-201-C type pH composite electrode, ZWY-211C constant temperature, Constant temperature incubator, Nucleic acid electrophoresis equipment, Protein electrophoresis equipment, and other equipment. digital pH meter (PHS-25, Shanghai Instrument and Electric Scientific Instrument Co., Ltd.), E-201-C type pH composite electrode.

Site-directed mutagenesis kit was purchased from Trans Gen (Beijing, China). Restriction endonuclease (EcoR I, Not I), DNA marker, and protein marker were purchased from TaKaRa (Otsu, Japan). Pichia pastoris GS115 cells were purchased from Invitrogen (Shanghai, China). Mutant primers were synthesized by Shuoqing (Kunming, China). The Thermomyces lanuginosus lipase gene (TLL) cloned in the pPIC9K vector was deposited in our laboratory. All other chemicals were commercially available and of analytical grade.

Tuberous roots of purple, yellow, red, and white (flesh) sweet potatoes (Ipomoea batatas L.) were purchased from the Jiangnan Market of Agricultural Products, Guangzhou, China. The aerial parts (vine stems and leaves) of sweet potato were obtained from a local farmer. The plant materials were cleaned with water and used directly for extraction of fresh material or for the extraction of dried material after air-dried for three more days. Except for the screening of peroxidase activity in different kinds and different parts of sweet potato which used fresh plant materials, air-dried old stems and leaves of the white (flesh) sweet potato were used in all other experiments. Young stems means the top 10 cm stems with young leaves, and the other part of the stem is called the old stem. Air-dried old stems were pulverized with a grinder and then sieved through 40 mesh sieve. The powder smaller than 40 mesh was used for extraction of peroxidases and phenolics.
Protein marker is purchased from Takara Co. (Shanghai, China). Bovine serum albumin, Coomassie brilliant blue R-250 and G250, and rutin were purchased from Sigma-Aldrich (St. Louis, MO, USA). HPLC-grade methanol was purchased from Honeywell (Maurice, NJ, USA). Other chemical and biochemical reagents are analytical or biochemical grade and were purchased from local supplier.

Xanthomonas oryzae pv. Oryzae (CCTCC AB 91123) was obtained from China-Center for Type Culture Collection, Wuhan University (Wuhan, China), and cultured as previously described (Byul et al. 2011 (link)). Both E. coli DH5α used for gene cloning and E. coli BL21 (DE3) serving as an expression host were purchased from TaKaRa Biotechnology Co. Ltd (Dalian, China). E. coli strains were routinely grown in LB broth or on LB agar plates with 100 µg/ml of ampicillin at 37 °C. The pMD19-T vector and pET-22b (+) vector were purchased from Invitrogen Corp. (Shanghai, China), and used for cloning and expression studies, respectively.
DNA Marker, Protein Marker, GoldView, T4 DNA ligase, PrimeSTAR HS DNA Polymerase, QuickCutTM Nde I and QuickCutTM Xho I restriction enzymes were purchased from TaKaRa Biotechnology Co., Ltd (Dalian, China). A bacterial genome extraction kit, a DNA fragment purification kit, an agarose gel DNA purification kit and a MiniBEST Plasmid Purification Kit were purchased from Sangon Biotechnology Co., Ltd. (Shanghai, China). All aqueous solutions and buffers were prepared with water purified with an in-house Milli-Q Plus System (Millipore, Inc., Billerica, MA, USA). All the other chemicals were of analytical grade.