瑞士乳杆菌细胞壁蛋白酶提取研究

瑞士乳杆菌细胞壁蛋白酶是其蛋白水解系统中一个非常重要的蛋白酶。本实验采用螯合Ca2+的方法对瑞士乳杆菌细胞壁蛋白酶的提取进行了研究,并确定了细胞壁蛋白酶提取的最佳实验条件。菌体用含有30mmol/LCaCl2的50mmol/LTris-HCl(pH7.10)缓冲液洗涤三次,然后用含有45mmol/LEDTA-Na2的50mmol/LTris-HCl(pH6.50)缓冲液悬浮,43℃保温,蛋白酶就会释放出来,90min后取出离心(4500r/min,20min,4℃),上清液即为粗酶液。粗酶液再经DEAE Sepharose CL-6B纯化,比酶活力提高了1.8倍。

Purification of Cell-envelope Proteinase from Lactobacillus helveticus

The cell-envelope proteinase (CEP) was a key-enzyme in proteolytic system of Lactobacillus helveticus. In this paper, the calcium-free method was used to purify the CEP, and the best method of purify CEP was found in this article. Cells were washed three times in 50 mmol/L Tris-HCl (pH7.10) containing 30 mmol/L CaCl2. The proteolytic activity was released from the washed cells by incubation of 50 mmol/L Tris-HCl (pH7.10), containing 45mmol/L EDTA-Na2 at 43 ℃. After 90 min of incubation, the cells were removed by centrifugation(4500r/min×20min, 4 ℃), CEP was in the supernatant. Specific activity of CEP was improved 1.8 times purified by DEAE Sepharose CL-6B.