Neutrase

Hetian chicken was purchased from the Hetian Chicken Development Co., Ltd. (Fujian, China). Neutrase, Bromelain, Papain, Flavourzyme, and Protamex were obtained from the Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). CTX was purchased from the Jiangsu Hengrui Medicine Co., Ltd. (Jiangsu, China). The CAR and ANS standards were acquired from the Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Levamisole was purchased from the Novozymes (China) Investment Co., Ltd. (Beijing, China). Roswell Park Memorial Institute (RPMI) 1640 medium and fetal bovine serum (FBS) were procured from Gibco (Grand Island, NY, USA). Concanavalin A (con A) and 3[4,5-dimethylththiazoyl-2-yl]2,5-diphenyltetrazolium bromide (MTT) were purchased from Sigma Aldrich Co. (St Louis, MO, USA). The enzyme-linked immunosorbent assay (ELISA) kits for the immunoglobulin M (IgM), immunoglobulin G (IgG), immunoglobulin A (IgA), interleukin-2 (IL-2), interleukin-10 (IL-10), interferon-gamma (IFN-γ), nitric oxide (NO), cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA) were purchased from the Meimian Biotechnology Co. Ltd. (Jiangsu, China). All chemical reagents were of analytical grade.

The water used in this study was deionized (18 MΩ·cm) from Water Purification System. Sephadex G-100, DEAE-52, 2,2-diphenyl-1-picrylhydrazyl, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid, 2,4,6-tri(2-pyridyl)-s-triazine, 6-hydroxy-2,5,7,8-tetramethlchroman-2-carboxylic acid, casein, glacial acetic acid, Tris-base, alcalase, trypsin, papain, neutrase, pepsin, and ammonium persulfate were purchased from Yuanye Biotech Co. Shanghai, China. Absolute ethanol (analytical grade), acetic acid, acetone, ferric chloride, ferrous sulphate, glucose, methanol (analytical grade), perchloric acid, phenol (redistilled reagent grade), potassium per-sulphate, potassium sulphate, sodium acetate, and sodium hydroxide were purchased from DaMao Chemical Co. Tianjin, China. Boric acid, copper sulfate, hydrochloric acid, methylene blue indicator, methyl red indicator, petroleum ether, sulfuric acid, and sodium thiosulfate were purchased from Guangzhou Chemical Co. (Guangzhou, China). Bovine serum albumin, Tris-HCl buffer, SDS, tetramethylethylenediamine were obtained from Sigma Chemical Co. (St. Louis, MO, USA) RIPA lysis buffer, acrylamide/bis-acrylamide mix, ladder protein, were purchased from Thermo Fisher Scientific Co. (Shanghai, China). All other chemicals were of analytical grade.

Okra seeds were purchased from a local farm then defatted refer to our previous research (Yao et al., 2019). After drying in oven at 60°C, the OSM powder was ground and then stored in fridge by vacuum packing. Its crude protein content was 36.9 ± 0.2% detected by Kjeldahl method.
2, 2‐Azino‐bis [3‐ethylbenzthiazoline‐6‐sulfonic acid]‐diammonium salt (ABTS) was purchased from Shanghai Aladdin Bio‐Chem Technology Co., Ltd. Neutrase, Papain, and Alkaline protease were purchased from Shanghai Yuanye Bio‐Technology Co., Ltd. Other reagents were purchased from Nanjing Shoude Chemicals Ltd. All the above reagents were of analytical grade.