The effects of tyrosine nitration on the structure and function of hen egg-white lysozyme.
The effects of tyrosine nitration on the structure and function of hen egg-white lysozyme.
复制标题
酪氨酸硝化对鸡蛋清溶菌酶结构和功能的影响
DOI：
10.1042/bj3150473
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
J. Heptinstall
中科院分区：
文献类型：
--
作者：
P. Richards;D. Walton;J. Heptinstall
本文研究了23位或20 + 23位酪氨酸硝化（生成弱酸3-硝基酪氨酸）对鸡蛋清溶菌酶结构和功能的影响。酶对藤黄微球菌细胞壁碎片或可溶性底物的活性表现出两种现象。(a)可溶性低聚物和多聚物水解的Km和kcat降低，导致硝化时催化效率（kcat/Km）仅发生微小变化。(b)水解M.黄体细胞壁碎片似乎受与蛋白质的静电相互作用支配，当3-硝基酪氨酰基被电离时，酶活性降低。从M.卢特斯消除了这种影响。还发现3-硝基酪氨酸基团作为溶菌酶中暴露的色氨酸残基的荧光猝灭剂。
We have investigated the effects of tyrosine nitration (to form the weak acid, 3-nitrotyrosine) at positions 23 or 20 plus 23, on the structure and function of hen egg-white lysozyme. Enzyme activity against Micrococcus luteus cell-wall fragments or soluble substrates exhibits two phenomena. (a) A decrease in Km and kcat for the hydrolysis of soluble oligo- and poly-saccharides, resulting in only minor changes in the catalytic efficiency (kcat/Km) upon nitration. (b) The hydrolysis of M. luteus cell-wall fragments appeared to be dominated by electrostatic interactions with the protein, giving a decrease in enzyme activity as the 3-nitrotyrosyl group became ionized. Removal of the cell-wall anionic polymer, teichuronic acid, from M. luteus abolished this effect. The 3-nitrotyrosine group was also found to act as a fluorescence quencher of exposed tryptophan residues in lysozyme.