Identification of a histidine residue essential for enzymatic activity of group B streptococcal hyaluronate lyase.
Identification of a histidine residue essential for enzymatic activity of group B streptococcal hyaluronate lyase.
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鉴定对 B 组链球菌透明质酸裂解酶的酶活性至关重要的组氨酸残基。
DOI：
10.1006/bbrc.1997.6107
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Pritchard,DG
中科院分区：
文献类型：
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作者：
Lin,B;Averett,WF;Pritchard,DG
B 族链球菌 (GBS) 产生的透明质酸裂解酶可将透明质酸完全降解为不饱和二糖单元，并裂解硫酸软骨素的非硫酸化区域。该酶被焦碳酸二乙酯迅速灭活，并且通过羟胺处理恢复酶活性，表明活性位点中存在组氨酸残基。 GBS 透明质酸裂解酶和其他四种相关酶的氨基酸序列比较表明，该酶的 16 个组氨酸残基之一 (His-479) 存在于高度保守的区域。通过定点诱变将 His-479 转化为甘氨酸导致修饰蛋白的酶活性完全丧失。我们推测 His-479 位于 GBS 透明质酸裂解酶的活性位点，并参与从透明质酸的葡萄糖醛酸残基中最初提取氢离子。
Hyaluronate lyase produced by group B streptococci (GBS) degrades hyaluronan completely to unsaturated disaccharide units and also cleaves unsulfated regions of chondroitin sulfate. The enzyme is rapidly inactivated by diethyl pyrocarbonate and enzymatic activity is restored by treatment with hydroxylamine, suggesting that a histidine residue is present in the active site. Amino acid sequence comparisons of GBS hyaluronate lyase and four other related enzymes revealed that one of the 16 histidine residues of the enzyme (His-479) is present in a highly conserved region. Conversion of His-479 to a glycine by site-directed mutagenesis resulted in a complete loss of enzymatic activity of the modified protein. We propose that His-479 is in the active site of GBS hyaluronate lyase and participates in the initial abstraction of hydrogen ions from the glucuronic acid residues of hyaluronan.