影响茂原链霉菌TGase产量关键蛋白酶的确定

Determination of key protease for TGase yield from Streptomyces mobaraensis

茂原链霉菌谷氨酰胺转氨酶(TGase)是一种能够改变蛋白质功能特性的交联酶。茂原链霉菌发酵过程中,TGase以酶原(Pro-TGase)的形式分泌到细胞外,再由胞外的金属蛋白酶和丝氨酸蛋白酶激活,形成有活力的TGase。为了确定Pro-TGase激活的最关键蛋白酶,采用在培养过程中,分别向对照培养基和MgCl2培养基中添加这2种蛋白酶抑制剂(EDTA和PMSF)的方式,抑制2种酶的活力,测定TGase在发酵过程中的活力变化。结果发现加入EDTA后,发酵上清液中的TGase活力不再升高;而加入PMSF后,发酵上清液中的TGase活力变化不明显。这些结果表明,金属蛋白酶是影响TGase合成的最关键蛋白酶。

Transglutaminase （TGase） from Streptomyces mobaraensis is a kind of cross-linking enzyme which can change the functional properties of protein. During the fermentation of S. mobaraensis, TGase was secreted to the ex- tracellular in the form of Pro-TGase. The Pro-TGase was activated by extracellular metalloprotease and serine protease to form an active TGase. In order to determine which one was the most important protease, two kinds of protease in- hibitors （EDTA and PMSF） were added into the media in the process of fermentation. Results showed that TGase ac- tivity in fermentation supernatant didnt increase any more when EDTA was supplemented. However, when PMSF was supplemented, the change of TGase activity was not obvious. These results indicated that the metalloprotease is the key enzyme for TGase synthesis.