文章基本信息

标题：α1-Antitrypsin Portland, a bioengineered serpin highly selective for furin: Application as an antipathogenic agent
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作者：François Jean ; Kori Stella ; Laurel Thomas 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：13
页码：7293-7298
DOI：10.1073/pnas.95.13.7293
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The important role of furin in the proteolytic activation of many pathogenic molecules has made this endoprotease a target for the development of potent and selective antiproteolytic agents. Here, we demonstrate the utility of the protein-based inhibitor 1-antitrypsin Portland (1-PDX) as an antipathogenic agent that can be used prophylactically to block furin-dependent cell killing by Pseudomonas exotoxin A. Biochemical analysis of the specificity of a bacterially expressed His- and FLAG-tagged 1-PDX (1-PDX/hf) revealed the selectivity of the 1-PDX/hf reactive site loop for furin (Ki, 600 pM) but not for other proprotein convertase family members or other unrelated endoproteases. Kinetic studies show that 1-PDX/hf inhibits furin by a slow tight-binding mechanism characteristic of serpin molecules and functions as a suicide substrate inhibitor. Once bound to furin's active site, 1-PDX/hf partitions with equal probability to undergo proteolysis by furin at the C-terminal side of the reactive center -Arg355-Ile-Pro-Arg358-{downarrow} or to form a kinetically trapped SDS-stable complex with the enzyme. This partitioning between the complex-forming and proteolytic pathways contributes to the ability of 1-PDX/hf to differentially inhibit members of the proprotein convertase family. Finally, we propose a structural model of the 1-PDX-reactive site loop that explains the high degree of enzyme selectivity of this serpin and which can be used to generate small molecule furin inhibitors.