Ecotin is a potent inhibitor of the contact system proteases factor XIIa and plasma kallikrein

FEBS Letters

Lindquist, Robert N.¹  Dennis, Mark S.¹  Ulmer, Jana S.¹  Lazarus, Robert A.¹ 

[1] Department of Protein Engineering, Genentech Inc., 460 Point San Bruno Boulevard, South San Francisco, CA 94080, USA

关键词: Ecotin;    Factor XIIa;    Kallikrein;    Serine protease inhibitor;    Anticoagulant;    HMWK;    high molecular weight kininogen;    DIC;    disseminated intravascular coagulation;    FXIIa;    factor XIIa;    FXa;    factor Xa;    SDS;    sodium dodecyl sulfate;    PAGE;    polyacrylamide gel electrophoresis;    PVDF;    polyvinylidene difluoride;    APTT;    activated partial thromboplastin time;    PT;    prothrombin time;   

DOI  :  10.1016/0014-5793(95)00466-M

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Ecotin, a serine protease inhibitor found in the periplasm of Escherichia coli, has been characterized as a potent reversible tight-binding inhibitor of the human contact activation proteases factor XIIa (FXIIa) and plasma kallikrein, having K _i values of 89 pM and 163 pM, respectively. Ecotin also inhibited human leukocyte elastase (HLE) with high affinity (K _i = 55 pM). The association rate constants k _on for FXIIa and kallikrein were 5.3 × 10⁵ M⁻¹·s⁻¹ and 2.9 × 10⁵ M⁻¹·s⁻¹, respectively. The dissociation rate constant k _off for kallikrein, measured in the presence of HLE to prevent reassociation, was 6.3 × 10⁻⁵ s⁻¹; the k _off for ecotin with FXIIa was 4.7 × 10⁻⁵ s⁻¹. Both FXIIa and kallikrein cleaved ecotin slowly at pH 5.0, identifying Met-84 as the P₁ residue. The potent anticoagulant effect by ecotin is explained by the coincident inhibition of FXIIa, kallikrein, and FXa and suggests that it may be useful in the study of inflammatory or thrombotic disorders such as sepsis or cardiopulmonary bypass.

【 授权许可】

Unknown