Characterization of Lys-698-to-Met substitution in human plasminogen catalytic domain.
Characterization of Lys-698-to-Met substitution in human plasminogen catalytic domain.
复制标题
人纤溶酶原催化结构域中 Lys-698-to-Met 取代的表征。
DOI：
10.1002/prot.20070
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Zhang,XuejunC
中科院分区：
文献类型：
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作者：
Terzyan,Simon;Wakeham,Nancy;Zhai,Peng;Rodgers,Karla;Zhang,XuejunC
链激酶（SK）是由链球菌分泌的人纤溶酶原（Pg）激活剂。SK的激活机制不同于生理性Pg激活剂，因为SK不是蛋白酶，不能蛋白水解激活Pg。相反，它与Pg形成紧密的复合物，蛋白水解激活其他Pg分子。假设人Pg的残基Lys-698参与触发SK-Pg复合物的激活。在这里，我们报告了一项在含有蛋白水解活化抗性背景（R561 A）的Pg（μPg）催化结构域中Lys-698替换为Met的研究。虽然它仍然有能力与SK形成复合物，保持相当的平衡解离常数（KD），但重组蛋白在与天然SK混合时，相对于其R561 A背景，其酰胺分解活性降低了近60倍。该突变体μPg的2.3 nm晶体结构证实了该重组蛋白的正确折叠。结合其他生物化学数据，这些结果支持以下前提：人Pg的Lys-698在SK. Proteins 2004的所谓N-末端插入激活机制中发挥功能性作用。© 2004 Wiley利斯公司
Streptokinase (SK) is a human plasminogen (Pg) activator secreted by streptococci. The activation mechanism of SK differs from that of physiological Pg activators in that SK is not a protease and cannot proteolytically activate Pg. Instead, it forms a tight complex with Pg that proteolytically activates other Pg molecules. The residue Lys‐698 of human Pg was hypothesized to participate in triggering activation in the SK–Pg complex. Here, we report a study of the Lys‐698 to Met substitution in the catalytic domain of Pg (μPg) containing the proteolytic activation‐resistant background (R561A). While it remains competent in forming a complex with SK, maintaining a comparable equilibration dissociation constant (KD), the recombinant protein shows a nearly 60‐fold reduction in amidolytic activity relative to its R561A background when mixed with native SK. A 2.3 Å crystal structure of this mutant μPg confirmed the correct folding of this recombinant protein. Combined with other biochemical data, these results support the premise that Lys‐698 of human Pg plays a functional role in the so‐called N‐terminal insertion activation mechanism by SK. Proteins 2004. © 2004 Wiley‐Liss, Inc.