Posttranslational Modifications of Lysozyme

利用基因修饰技术研究了蛋白质糖基化和亲脂化等翻译后修饰对鸡蛋白色溶菌酶功能特性的影响。通过定点突变在19和49位构建N-连接糖基化信号（Asn-X-Thr/Ser）。由此获得的多甘露糖溶菌酶对提高热稳定性和乳化性以及降低致敏性非常有效。虽然通过在N-末端连接N-肉豆蔻酰化信号序列来检测溶菌酶的脂质化，但溶菌酶的折叠不能产生未折叠的形式。在溶菌酶的C-末端引入了与肉豆蔻酸长度相同的疏水肽，取代了亲脂作用。疏水吸附溶菌酶（H5）对革兰氏阴性菌有较强的抗菌活性。将这些修饰过的溶菌酶插入烟草中以提高其杀菌作用。转基因烟草对灰霉病表现出较强的抗性。

Effects of post-translational modification such as glycosylation and lipophilization on the functional properties of hen egg white lysozyme were investigated in yeast expression system using genetic modification. The N-linked glycosylation signal (Asn-X-Thr/Ser) was constructed in the position 19 and 49 by site-directed mutagenesis. The polymannosy lysozyme thus obtained was very effective to enhance the thermal stability and the emulsifying property and to decrease the allergenicity. Although the lipophization of lysozyme was examined by the attachment of N-myristylation signal sequence into N-terminal, the folding of lysozyme failed to produce the unfolded form. Instesd of lipophilization, the hydrophobic peptide having the same length as myristic acid was attached to C-terminal of lysozyme. The hydrophobic attached lysozyme (H5) revealed a strong antimicrobial activity agianst Gram-negative bacteria. These modified lysozymes were inserted into tobacco to improve the bactericial action. The transgenic tobacco showed a strong resistance to gray mold.