1oph: Difference between revisions
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==Overview== | ==Overview== | ||
The serpin antithrombin is a slow thrombin inhibitor that requires heparin | The serpin antithrombin is a slow thrombin inhibitor that requires heparin to enhance its reaction rate. In contrast, alpha1-proteinase inhibitor (alpha1PI) Pittsburgh (P1 Met --> Arg natural variant) inhibits thrombin 17 times faster than pentasaccharide heparin-activated antithrombin. We present here x-ray structures of free and S195A trypsin-bound alpha1PI Pittsburgh, which show that the reactive center loop (RCL) possesses a canonical conformation in the free serpin that does not change upon binding to S195A trypsin and that contacts the proteinase only between P2 and P2'. By inference from the structure of heparin cofactor II bound to S195A thrombin, this RCL conformation is also appropriate for binding to thrombin. Reaction rates of trypsin and thrombin with alpha1PI Pittsburgh and antithrombin and their P2 variants show that the low antithrombin-thrombin reaction rate results from the antithrombin RCL sequence at P2 and implies that, in solution, the antithrombin RCL must be in a similar canonical conformation to that found here for alpha1PI Pittsburgh, even in the nonheparin-activated state. This suggests a general, limited, canonical-like interaction between serpins and proteinases in their Michaelis complexes. | ||
==Disease== | ==Disease== | ||
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[[Category: Trypsin]] | [[Category: Trypsin]] | ||
[[Category: Dementiev, A.]] | [[Category: Dementiev, A.]] | ||
[[Category: Gettins, P | [[Category: Gettins, P G.]] | ||
[[Category: Simonovic, M.]] | [[Category: Simonovic, M.]] | ||
[[Category: Volz, K.]] | [[Category: Volz, K.]] | ||
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[[Category: trypsin]] | [[Category: trypsin]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:20:10 2008'' | ||
Revision as of 15:20, 21 February 2008
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NON-COVALENT COMPLEX BETWEEN ALPHA-1-PI-PITTSBURGH AND S195A TRYPSIN
OverviewOverview
The serpin antithrombin is a slow thrombin inhibitor that requires heparin to enhance its reaction rate. In contrast, alpha1-proteinase inhibitor (alpha1PI) Pittsburgh (P1 Met --> Arg natural variant) inhibits thrombin 17 times faster than pentasaccharide heparin-activated antithrombin. We present here x-ray structures of free and S195A trypsin-bound alpha1PI Pittsburgh, which show that the reactive center loop (RCL) possesses a canonical conformation in the free serpin that does not change upon binding to S195A trypsin and that contacts the proteinase only between P2 and P2'. By inference from the structure of heparin cofactor II bound to S195A thrombin, this RCL conformation is also appropriate for binding to thrombin. Reaction rates of trypsin and thrombin with alpha1PI Pittsburgh and antithrombin and their P2 variants show that the low antithrombin-thrombin reaction rate results from the antithrombin RCL sequence at P2 and implies that, in solution, the antithrombin RCL must be in a similar canonical conformation to that found here for alpha1PI Pittsburgh, even in the nonheparin-activated state. This suggests a general, limited, canonical-like interaction between serpins and proteinases in their Michaelis complexes.
DiseaseDisease
Known diseases associated with this structure: Emphysema OMIM:[107400], Emphysema-cirrhosis OMIM:[107400], Hemorrhagic diathesis due to antithrombin Pittsburgh OMIM:[107400], Pulmonary disease, chronic obstructive, susceptibility to OMIM:[107400]
About this StructureAbout this Structure
1OPH is a Protein complex structure of sequences from Bos taurus and Homo sapiens. Active as Trypsin, with EC number 3.4.21.4 Full crystallographic information is available from OCA.
ReferenceReference
Canonical inhibitor-like interactions explain reactivity of alpha1-proteinase inhibitor Pittsburgh and antithrombin with proteinases., Dementiev A, Simonovic M, Volz K, Gettins PG, J Biol Chem. 2003 Sep 26;278(39):37881-7. Epub 2003 Jul 14. PMID:12860985
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