X-ray crystallography and structural stability of digestive lysozyme from cow stomach
X-ray crystallography and structural stability of digestive lysozyme from cow stomach
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DOI：
10.1111/j.1742-4658.2009.06948.x
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发表时间：
2009-04-01
期刊：
影响因子：
5.4
通讯作者：
Kawano, Keiichi
中科院分区：
文献类型：
--
作者：
Nonaka, Yasuhiro;Akieda, Daisuke;Kawano, Keiichi
在反刍动物、一些食叶动物和一些昆虫中，防御性溶菌酶已经被适应为消化酶，以消化胃中的细菌。据报道，消化溶菌酶对蛋白酶具有抗性，并在酸性ph下具有最佳活性。在恶劣的胃条件下提供持续的分解活性的适应性的结构基础尚不清楚。在这项研究中，我们获得了重组牛胃溶菌酶2 （BSL2）的晶体结构。我们的变性和热展开实验表明，BSL2在酸性ph下具有很高的构象稳定性。这种高稳定性可能与BSL2在酸性溶液中的胃蛋白酶抗性有关。BSL2的晶体结构表明，带负电荷的表面、短环和盐桥可以提供结构稳定性，从而抵抗胃蛋白酶。BSL2可能在中性pH下失去裂解活性，因为它适应于抵抗胃蛋白酶。
In ruminants, some leaf-eating animals, and some insects, defensive lysozymes have been adapted to become digestive enzymes, in order to digest bacteria in the stomach. Digestive lysozyme has been reported to be resistant to protease and to have optimal activity at acidic pH. The structural basis of the adaptation providing persistence of lytic activity under severe gastric conditions remains unclear. In this investigation, we obtained the crystallographic structure of recombinant bovine stomach lysozyme 2 (BSL2). Our denaturant and thermal unfolding experiments revealed that BSL2 has high conformational stability at acidic pH. The high stability in acidic solution could be related to pepsin resistance, which has been previously reported for BSL2. The crystal structure of BSL2 suggested that negatively charged surfaces, a shortened loop and salt bridges could provide structural stability, and thus resistance to pepsin. It is likely that BSL2 loses lytic activity at neutral pH because of adaptations to resist pepsin.