Effects of Additives on Irreversible Inactivation of Lysozyme at Neutral pH and 100° C
Effects of Additives on Irreversible Inactivation of Lysozyme at Neutral pH and 100° C
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中性 pH 值和 100°C 条件下添加剂对溶菌酶不可逆失活的影响
DOI：
10.1093/jb/117.2.369
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发表时间：
1995
影响因子：
2.7
通讯作者：
T. Imoto
中科院分区：
文献类型：
--
作者：
H. Tomizawa;H. Yamada;K. Tanigawa;T. Imoto
研究了溶菌酶在中性pH和100 ℃下的不可逆失活机理及添加剂对失活的影响。溶菌酶在中性pH下的热失活是由分子内和分子间的二硫键交换以及不可逆变性溶菌酶的产生引起的，该变性溶菌酶通过除二硫键交换之外的多种化学反应而不稳定。此外，单独地，脱酰胺通过引起溶菌酶的正电荷和细菌细胞壁的负电荷之间的静电相互作用的减少而轻微地影响灭活。至于添加剂对失活的影响，少量铜离子通过催化空气氧化热诱导的痕量游离硫醇和有机试剂来抑制分子内和分子间的二硫键交换（乙酰胺，乙醇，和甘油）通过改变可解离残基的pKa值，将失活机制改变为酸性条件下的失活机制，并通过降低疏水相互作用
The mechanism of irreversible inactivation of lysozyme at neutral pH at 100 degrees C, and effects of additives on the inactivation were investigated. The thermoinactivation of lysozyme at neutral pH was caused by intra- and intermolecular disulfide exchange and the production of irreversibly denatured lysozyme, which was destabilized by multiple chemical reactions other than disulfide exchange. In addition, independently, deamidation slightly affected the inactivation by causing a decrease of electrostatic interaction between positive charges of lysozyme and negative charges of the bacterial cell wall. As for the effects of additives on the inactivation, a small amount of copper ion suppressed intra- and intermolecular disulfide exchange by catalyzing air oxidation of heat-induced trace amounts of free thiols, and organic reagents (acetamide, ethanol, and glycerol) changed the mechanism of the inactivation to that under acidic conditions by shifting the pKa values of dissociable residues and also suppressed intermolecular disulfide exchange by decreasing hydrophobic interactions.