1id5
From Proteopedia
CRYSTAL STRUCTURE OF BOVINE THROMBIN COMPLEX WITH PROTEASE INHIBITOR ECOTIN
Structural highlights
Function[THRB_BOVIN] Thrombin, which cleaves bonds after Arg and Lys, converts fibrinogen to fibrin and activates factors V, VII, VIII, XIII, and, in complex with thrombomodulin, protein C. Functions in blood homeostasis, inflammation and wound healing (By similarity). [ECOT_ECOLI] General inhibitor of pancreatic serine proteases: inhibits chymotrypsin, trypsin, elastases, factor X, kallikrein as well as a variety of other proteases. The strength of inhibition does not appear to be correlated with a particular protease specificity.[HAMAP-Rule:MF_00706] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe protease inhibitor ecotin fails to inhibit thrombin despite its broad specificity against serine proteases. A point mutation (M84R) in ecotin results in a 1.5 nM affinity for thrombin, 10(4) times stronger than that of wild-type ecotin. The crystal structure of bovine thrombin is determined in complex with ecotin M84R mutant at 2.5 A resolution. Surface loops surrounding the active site cleft of thrombin have undergone significant structural changes to permit inhibitor binding. Particularly, the insertion loops at residues 60 and 148 in thrombin, which likely mediate the interactions with macromolecules, are displaced when the complex forms. Thrombin and ecotin M84R interact in two distinct surfaces. The loop at residue 99 and the C-terminus of thrombin contact ecotin through mixed polar and nonpolar interactions. The active site of thrombin is filled with eight consecutive amino acids of ecotin and demonstrates thrombin's preference for specific features that are compatible with the thrombin cleavage site: negatively charged-Pro-Val-X-Pro-Arg-hydrophobic-positively charged (P1 Arg is in bold letters). The preference for a Val at P4 is clearly defined. The insertion at residue 60 may further affect substrate binding by moving its adjacent loops that are part of the substrate recognition sites. Crystal structure of thrombin-ecotin reveals conformational changes and extended interactions.,Wang SX, Esmon CT, Fletterick RJ Biochemistry. 2001 Aug 28;40(34):10038-46. PMID:11513582[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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