Inagaki T, Katayama M, Miura K
J Nutr Sci Vitaminol (Tokyo). 1979;25(4):333-42. doi: 10.3177/jnsv.25.333.
Four chromatographically different proteases were partially purified from defatted soybean flour, and their pH optima were around 5.0 to 5.6 using casein as the substrate. These soybean proteases were designated S1, S2, S3 and S4 according to their order of elution from a DEAE-cellulose column. Each gave a single peak of caseinolytic activity on a Sephadex G-200 column chromatogram, and corresponded to the molecular weights of about 50,000(S1), 35,000(S2), 60,000(S3) and 200,000(S4). The proteases could hydrolyze casein and poly-Glu. alpha-Casein was more rapidly hydrolyzed than beta-casein, but the esters or dipeptide could not be hydrolyzed. Aliquots of 10(-3) M Hg2+, Cu2+ and Zn2+ inhibited the caseinolytic activities by 70% to 90%, while other cations, Mn2+, Mg2+, Ca2+ and Ni2+, at the same concentration did not. SPI (10(-5) M) inhibited 80--90% of their activities, and EPNP (10(-5) M) inhibited their activities 30--60%, but DFP (10(-3) M), SSI (10(-3) M), PCMB (10(-4) M), NEM (10(-3) M) and EDTA (10(-3) M) were not inhibitory. The above results indicate that proteases S1, S2, S3 and S4 from defatted soybean flour can be classified as acid proteases.
从脱脂大豆粉中部分纯化出四种色谱性质不同的蛋白酶，以酪蛋白为底物时，它们的最适pH值在5.0至5.6左右。这些大豆蛋白酶根据其从DEAE - 纤维素柱上洗脱的顺序分别命名为S1、S2、S3和S4。在葡聚糖凝胶G - 200柱色谱图上，每种蛋白酶都给出了一个单一的酪蛋白水解活性峰，其分子量分别约为50,000（S1）、35,000（S2）、60,000（S3）和200,000（S4）。这些蛋白酶能够水解酪蛋白和聚谷氨酸。α - 酪蛋白比β - 酪蛋白水解得更快，但不能水解酯类或二肽。10⁻³ M的Hg²⁺、Cu²⁺和Zn²⁺等分试样可抑制70%至90%的酪蛋白水解活性，而相同浓度的其他阳离子Mn²⁺、Mg²⁺、Ca²⁺和Ni²⁺则不会。10⁻⁵ M的大豆分离蛋白（SPI）抑制其活性的80 - 90%，10⁻⁵ M的对硝基苯磷酸酯（EPNP）抑制其活性30 - 60%，但10⁻³ M的二异丙基氟磷酸（DFP）、10⁻³ M的大豆胰蛋白酶抑制剂（SSI）、10⁻⁴ M的对氯汞苯甲酸（PCMB）、10⁻³ M的N - 乙基马来酰亚胺（NEM）和10⁻³ M的乙二胺四乙酸（EDTA）没有抑制作用。上述结果表明，脱脂大豆粉中的蛋白酶S1、S2、S3和S4可归类为酸性蛋白酶。
