Characterization of proteases produced by virulent strain of Aeromonas

对嗜水气单胞菌产生的金属蛋白酶和黄曲霉产生的丝氨酸蛋白酶的性质进行了研究。嗜水气单胞菌在环境中产生金属蛋白酶作为中间体，它由成熟结构域和羧基末端结构域组成。释放到环境中的中间形式立即被裂解，以去除羧基末端结构域并转变为成熟形式。为了明确中间体的性质，我们构建了含有金属蛋白酶基因的质粒，并将其导入到大肠杆菌中。对转化细胞产生的金属蛋白酶的检测表明，虽然检测到成熟形式，但没有检测到中间体。结果表明，在25℃时，黄曲霉产丝氨酸蛋白酶的量比37℃时要多，而且在培养基中加入脱脂奶能促进黄曲霉产生丝氨酸蛋白酶。

The properties of metalloprotease produced by A. hydrophila and of serine protease produced by A. trota were examined. A. hydrophila produces the metalloprotease as the intermediate form, which is composed of mature domain and carboxy-terminal domain, into milieu. The intermediate form released into milieu is immediately cleaved to remove the carboxy-terminal domain and turns into mature form. To clear the property of the intermediate form, we constructed the plasmid harboring metalloprotease gene and introduced it into Escherichia coli. The examination of the metalloprotease produced by the transformed cell showed that the intermediate form is not detected, though the mature form is detected.Subsequently, I showed that A. trota produced much amount of serine protease at 25 degree than at 37 degree and that the addition of skim milk in the medium promoted the production of serine protease by A. trota.