Department of Biochemistry, Strathclyde University, Glasgow, Scotland.
Appl Environ Microbiol. 1979 Apr;37(4):719-24. doi: 10.1128/aem.37.4.719-724.1979.
Mucor pusillus was grown in different media for a period of 92 h, and the media were investigated for both milk-clotting and protease activities. It was observed that the ratio of extracellular milk-clotting activity to protease activity was the highest for 3% corn steep liquor containing 1% glucose as the source of carbon. Variation of both milk-clotting and protease activities was studied during the growth of the organism in the medium stated above. Separation of protease was carried out by ion-exchange chromatography at pH 8.0. Fractions collected were assayed for both activities simultaneously. The findings suggested that, instead of only one major acid protease, as reported by previous workers, two major acid proteases were produced. One of them had significant rennin-like activity, and the other lacked it. The former could be assumed to be the enzyme reported and studied by previous workers. The existence of two proteases was further confirmed by the appearance of two protease activity bands on polyacrylamide gels after electrophoresis. An attempt was made to separate the rennin-like enzyme from nonspecific protease activity by ammonium sulfate fractionation followed by ion-exchange chromatography at pH 6.0. The results indicated that the nonspecific protease activity due to the enzyme that lacked rennin action was substantially removed by the ammonium sulfate fractionation.
少根根霉在不同的培养基中培养了 92 小时，研究了这些培养基的凝乳酶活性和蛋白酶活性。结果表明，以 3%玉米浆和 1%葡萄糖作为碳源时，胞外凝乳酶活性与蛋白酶活性之比最高。在上述培养基中研究了微生物生长过程中凝乳酶和蛋白酶活性的变化。在 pH 值 8.0 时，通过离子交换层析对蛋白酶进行分离。同时收集各馏分并测定其活性。研究结果表明，与之前研究人员的报道不同，并非只有一种主要的酸性蛋白酶，而是产生了两种主要的酸性蛋白酶。其中一种具有显著的凝乳酶样活性，而另一种则缺乏这种活性。前者可以被认为是之前的研究人员报道和研究的酶。两种蛋白酶的存在通过电泳后聚丙烯酰胺凝胶上出现的两条蛋白酶活性带得到进一步证实。尝试通过硫酸铵分级分离然后在 pH 值 6.0 时进行离子交换层析，从非特异性蛋白酶活性中分离出凝乳酶样酶。结果表明，由于缺乏凝乳酶作用的酶，非特异性蛋白酶活性通过硫酸铵分级分离得到了很大程度的去除。
