Potempa J, Porwit-Bobr Z, Travis J
Department of Microbiology and Immunology, Jagiellonian University, Kraków, Poland.
Biochim Biophys Acta. 1989 Dec 8;993(2-3):301-4. doi: 10.1016/0304-4165(89)90181-5.
Purified Staphylococcus aureus metalloproteinase contains trace amounts of a serine proteinase which rapidly degrades the metalloproteinase when EDTA is present. However, no degradation occurs when Ca2+ is added or if the serine proteinase is removed by immunoaffinity chromatography. Selective chelation of Zn2+ by o-phenanthroline, which reversibly inactivates the metalloproteinase, does not result in the degradation of the apometalloproteinase, even with excess of serine proteinase. These data are interpreted as follows: EDTA chelates enzyme-bound Ca2+ and Zn2+, causing irreversible inactivation as well as a conformational change in the metal-free protein. This allows proteolysis by the contaminating serine proteinase and explains why the metalloproteinase purified from serine proteinase-deficient strains of S. aureus was previously thought to be stable to autolysis.
纯化的金黄色葡萄球菌金属蛋白酶含有痕量的丝氨酸蛋白酶，当存在乙二胺四乙酸（EDTA）时，该丝氨酸蛋白酶会迅速降解金属蛋白酶。然而，添加钙离子（Ca2+）时不会发生降解，或者通过免疫亲和层析去除丝氨酸蛋白酶时也不会发生降解。邻菲罗啉对锌离子（Zn2+）的选择性螯合作用可使金属蛋白酶可逆失活，即使存在过量的丝氨酸蛋白酶，也不会导致脱辅基金属蛋白酶的降解。这些数据的解释如下：EDTA螯合与酶结合的Ca2+和Zn2+，导致不可逆失活以及无金属蛋白的构象变化。这使得污染的丝氨酸蛋白酶能够进行蛋白水解，并解释了为什么以前认为从缺乏丝氨酸蛋白酶的金黄色葡萄球菌菌株中纯化的金属蛋白酶对自溶稳定。
