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| [[Image:2hnt.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2hnt| PDB=2hnt | SCENE= }} | | {{STRUCTURE_2hnt| PDB=2hnt | SCENE= }} |
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| '''CRYSTALLOGRAPHIC STRUCTURE OF HUMAN GAMMA-THROMBIN'''
| | ===CRYSTALLOGRAPHIC STRUCTURE OF HUMAN GAMMA-THROMBIN=== |
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| ==Overview==
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| In an effort to prepare crystals and determine the structure of alpha-thrombin complexed to a synthetic peptide inhibitor (MDL-28050) of the hirudin 54-65 COOH-terminal region, it was discovered that the crystals were not those of the complex but of gamma-thrombin. Gel electrophoresis studies revealed that autolytic degradation had occurred prior to crystallization. NH2-terminal sequence analysis of these autolytic fragments confirmed the gamma-thrombin product (cleavages at Arg75-Tyr76 and/or Arg77A-Asn78, and Lys149E-Gly150; chymotrypsinogen numbering) with a minor amount of another autolysis product, beta-thrombin (first two cleavages only). The final structure has an R-factor of 0.156 for 7.0-2.5-A data, and includes 186 water molecules. A comparison of gamma-thrombin with the thrombin structure in the alpha-thrombin-hirugen complex revealed that the two structures agreed well (r.m.s. delta = 0.39 A for main chain atoms). These structures possess uninhibited active sites where the disposition of the catalytic triad residues is nearly identical. The electron density in the vicinity of the gamma-thrombin cleavage regions is poor, and only becomes well-defined several residues prior to and after the actual cleavage sites. The extensive disorder evoked by beta-cleavage(s) in the Lys70-Glu80 loop region indicates that this part of the molecule is severely disrupted by autolysis and is the reason exosite functions are dramatically impaired in beta-and gamma-thrombin. Since autolysis did not lead to a major reorganization of the folded structure of alpha-thrombin, the likely structural features of the interaction of thrombin substrate with thrombin enzyme during beta-cleavage have been modeled by docking the exosite region of one molecule at the active site of another.
| | The line below this paragraph, {{ABSTRACT_PUBMED_8071320}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 8071320 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_8071320}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Tulinsky, A.]] | | [[Category: Tulinsky, A.]] |
| [[Category: Serine protease]] | | [[Category: Serine protease]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 06:29:51 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 13:46:32 2008'' |
