Prins R A, van Rheenen D L, van't Klooster A T
Antonie Van Leeuwenhoek. 1983 Dec;49(6):585-95. doi: 10.1007/BF00399852.
Up to 43% of the viable bacteria from the rumen of cows fed grass and concentrates grew on a medium containing casein as the main substrate. Proteolytic counts for a cow fed on straw and concentrates or for a hay-fed cow were lower than counts for cows fed grass and concentrates, both in absolute terms and in relation to the total anaerobic count. In crude enzyme preparations derived from the rumen protozoa, amino acid arylamidase (leucine aminopeptidase)-like activity was the main proteolytic activity observed. In enzyme preparations extracted from the rumen bacteria in the presence of Triton X-100, trypsin-like activity was predominant. Amino acid arylamidase- and metal-chelating proteinase-like activity together with lower activities of carboxypeptidase A and B and a very low chymotrypsin-like activity were found as well. Studies with enzyme inhibitors showed that the bacterial trypsin-like activity was largely of the cysteine-protease type in a hay-fed cow, but in addition comprised serine-protease activity in a cow fed grass and concentrates. Total proteolytic activity of the enzymes in the bacterial fraction and the spectrum of proteolytic enzymes were found to vary with the ration.
以酪蛋白为主要底物的培养基上，高达43%来自喂食青草和精饲料的奶牛瘤胃中的活菌能够生长。无论是从绝对数量还是相对于总厌氧菌数量而言，喂食秸秆和精饲料的奶牛或喂食干草的奶牛的蛋白水解菌数量均低于喂食青草和精饲料的奶牛。在源自瘤胃原虫的粗酶制剂中，观察到的主要蛋白水解活性是氨基酸芳基酰胺酶（亮氨酸氨肽酶）样活性。在存在Triton X-100的情况下从瘤胃细菌中提取的酶制剂中，胰蛋白酶样活性占主导。还发现了氨基酸芳基酰胺酶和金属螯合蛋白酶样活性，以及较低的羧肽酶A和B活性和极低的胰凝乳蛋白酶样活性。酶抑制剂研究表明，在喂食干草的奶牛中，细菌的胰蛋白酶样活性主要是半胱氨酸蛋白酶类型，但在喂食青草和精饲料的奶牛中，还包括丝氨酸蛋白酶活性。发现细菌部分中酶的总蛋白水解活性和蛋白水解酶谱会因日粮不同而有所变化。
