Two commercial proteases (subtilisin-typed FNA from Bacillus amyloliquefaciens, and chymotrypsin-like NPP from Nocardiopsis prasina), porcine pepsin, porcine pancreatin having protease activity and their combinations were studied in vitro by LC-MS for their ability to digest soy protein isolate (SPI) under conditions close to those found in the stomach (pH 3.7) and small intestine (pH 6.5). The total number of peptides generated, and their size distribution were obtained under each set of the digestion conditions. These peptides were grouped according to their C-terminal amino acid (AA) residue (P1) and mass, based on which two concepts were proposed, i.e., Normalized Peptide Bond Cleavage Frequency (NPBCF) and Protease Substrate Broadness Index (PSBI). At pH 3.7, FNA+pepsin increased PSBI vs. pepsin alone by 2.7 and 4.9 percentage points (p.p.) at a SPI:protease ratio of 20:1 and 100:1, respectively. At pH 6.5, FNA+pancreatin improved PSBI by 9.1 and 10.2 p.p. at SPI:protease 20:1 and 100:1, respectively, vs. pancreatin alone. NPP generated 38% more peptides than FNA when administered with pancreatin at SPI:protease 200:1:1 and pH 6.5, but FNA alone (28.9) or FNA+pancreatin (29.1) gave a higher PSBI than pancreatin (22.2), NPP (20.3) and NPP+pancreatin (22.0). At pH 3.7 FNA generated 59% and 39% of peptides of pepsin at SPI:protease of 20:1 and 100:1, respectively, and both groups of peptides had similar size distribution. At pH 6.5 more small sized peptides were generated by FNA or FNA+pancreatin than pancreatin and NPP alone or pancreatin+NPP. In conclusion, FNA showed complementary effects with pepsin and pancreatin in terms of PSBI and generated more small sized peptides compared to NPP.

通过LC-MS在体外研究了两种商业蛋白酶（来自解淀粉芽孢杆菌的枯草杆菌蛋白酶型FNA和来自Nocardiopsis prasina的胰凝乳蛋白酶样NPP ），猪胃蛋白酶，猪胰酶及其组合，以研究其消化大豆分离蛋白能力SPI）在接近胃（pH 3.7）和小肠（pH 6.5）的条件下进行。在每组消化条件下均获得了产生的肽总数及其大小分布。这些肽根据在其上两个概念提出了，它们的C-末端氨基酸（AA）的残余物（P1）和质量，基于分组的我。Ë，标准化的肽键切割频率（NPBCF）和蛋白酶底物宽度指数（PSBI）。在pH 3.7下，FNA +胃蛋白酶与相比增加了PSBI 。单独的胃蛋白酶在SPI：蛋白酶比率为20：1和100：1时分别增加2.7和4.9个百分点（pp）。在pH 6.5时，FNA +胰酶在SPI：蛋白酶20：1和100：1时分别将PSBI提高9.1和10.2 pp，而。单独使用胰酶。当在SPI：蛋白酶200：1：1和pH 6.5下与胰酶一起施用时，NPP产生的肽比FNA多38％，但是单独的FNA（28.9）或FNA +胰酶（29.1）产生的PSBI高于胰酶（22.2），NPP（ 20.3）和NPP +胰酶（22.0）。在pH 3.7下，FNA在SPI：蛋白酶为20：1和100：1时分别产生59％和39％的胃蛋白酶肽，两组肽的大小分布相似。在pH 6.5时，FNA或FNA +胰酶比单独的胰酶和NPP或胰酶+ NPP产生的小肽更多。总之，与NPP相比，FNA在PSBI方面显示出与胃蛋白酶和胰酶的互补作用，并产生了更多的小分子肽。