Esumi H, Yasugi S, Mizuno T, Fujiki H
Biochim Biophys Acta. 1980 Feb 14;611(2):363-70. doi: 10.1016/0005-2744(80)90073-x.
A crude extract of the proventriculus of the Japanese quail gave at least five bands of peptic activity at pH 2.2 on polyacrylamide gel electrophoresis. The main component, constituting about 40% of the total acid protease activity, was purified to homogeneity by hydroxyapatite and DEAE-Sepharose column chromatographies. At below pH 4.0, the pepsinogen was converted to a pepsin, which had the same electrophoretic mobility as one of the five bands of peptic activity present in the crude extract. The molecular weights of the pepsinogen and the pepsin were 40 000 and 36 000, respectively. Quail pepsin was stable in alkali up to pH 8.5. The optimal pH of the pepsin on hemoglobin was pH 3.0. The pepsin had about half the milk-clotting activity of purified porcine pepsin, but the pepsinogen itself had no activity. The hydrolytic activity of quail pepsin on N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine was about 1% of that of porcine pepsin. Among the various protease inhibitors tested, only pepstatin inhibited the proteolytic activity of the pepsin. The amino acid composition of quail pepsinogen was found to be rather similar to that of chick pepsinogen C, and these two pepsinogens possessed common antigenicity.
日本鹌鹑前胃的粗提物在聚丙烯酰胺凝胶电泳上于pH 2.2时至少呈现出五条胃蛋白酶活性带。通过羟基磷灰石和DEAE-琼脂糖柱色谱法将占总酸性蛋白酶活性约40%的主要成分纯化至同质。在pH 4.0以下，胃蛋白酶原转化为胃蛋白酶，其电泳迁移率与粗提物中五条胃蛋白酶活性带之一相同。胃蛋白酶原和胃蛋白酶的分子量分别为40000和36000。鹌鹑胃蛋白酶在高达pH 8.5的碱性环境中稳定。该胃蛋白酶对血红蛋白的最适pH为3.0。该胃蛋白酶的凝乳活性约为纯化猪胃蛋白酶的一半，但胃蛋白酶原本身无活性。鹌鹑胃蛋白酶对N-乙酰-L-苯丙氨酰-3,5-二碘-L-酪氨酸的水解活性约为猪胃蛋白酶的1%。在测试的各种蛋白酶抑制剂中，只有胃蛋白酶抑制剂抑制该胃蛋白酶的蛋白水解活性。发现鹌鹑胃蛋白酶原的氨基酸组成与鸡胃蛋白酶原C相当相似，并且这两种胃蛋白酶原具有共同的抗原性。
