Soluble starch

1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) were purchased from Sigma Chemical Co. (St. Louis, MO, USA). Ferric-tripyridyltriazine (Fe³⁺-TPTZ) is purchased from Beyotime Biotechnology (Shanghai, China). Chromatographic grade analytical standards asparaginic acid, glutamic acid, asparagine, serine, glutamine, histidine, glycine, threonine, citrulline, arginine, alanine, tyrosine, cystine, valine, methionine, tryptophan, phenylalanine, isoleucine, leucine, lysine, hydroxyproline, proline, 5′-CMP, 5′-UMP, 5′-GMP, 5′-IMP, 5′-XMP, 5′-AMP, trehalose, mannitol, quininic acid, l-malic acid and fumaric acid purchased from Solarbio Science & Technology Co., Ltd. (Beijing, China). α-Amylase, α-glucosidase, 4-nitrophenyl α-d-glucopyranoside (PNPG), and soluble starch were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). All other reagents were analytical grade and obtained from Chengdu Kelong Chemical Factory (Chengdu, China).

The PrimeSTAR^® HS (Premix), Ex Taq^® DNA polymerase and T4 ligase were purchased from Takara Biotechnology (Dalian, China). Substrates, such as chitin, xylan, microcrystalline cellulose, soluble starch, and powdery chitosan with 85%, 90% and 95% degrees of deacetylation (DA), were from Yuanye Biotechnology (Shanghai, China). Chitosan oligosaccharides with different degree of polymerization (DP 1–6) were purchased from Qingdao BZ Oligo Biotech (Qingdao, China). Non-GMO soybeans (protein content 38%) were originally produced in Canada and supplied by Jinzai Food Group Co., Ltd. (Yueyang, China). All other chemical reagents were of analytical grade and purchased from the Guangzhou Chemical Reagent Co., Ltd. (Guangzhou, China).

Escherichia coli Trans5ɑ and BL21(DE3) (TransGen Biotech, Beijing, China) was used for plasmid maintenance and protein expression, respectively. T4 DNA ligase, NdeI, HindIII (New England Biolabs, Ipswich, MA, USA) and pET-28a + vector (Invitrogen, Carlsbad, CA, USA) were used for gene cloning. Ni-NTA Sefinose™ Resin was purchased from Sangon Biotech (Shanghai, China) for protein purification. p-Nitrophenyl-α-D-glucopyranoside (pNPαG), p-Nitrophenyl-β-D-glucopyranoside (pNPβG), p-Nitrophenyl-β-D-xylopyranoside (pNPβX), p-Nitrophenyl-α-D-mannopyranoside (pNPαM), and p-Nitrophenyl-α-L-arobinopyranoside (pNPαA) were from J&K Scientific (Beijing, China), while soluble starch, malto-oligosaccharides, Nigerose, Kojibiose, Isomaltose, Sucrose, Kanamycin sulphate, imidazole, isopropylthio-β-galactoside (IPTG) and other reagents were purchased from yuanye Bio-Technology (Shanghai, China).