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| ==Overview==
| | {{ABSTRACT_1942057}} |
| The isomorphous structures of the hirugen (N-acetylhirudin 53'-64' with sulfato-Tyr63') and hirulog 1 (D-Phe-Pro-Arg-Pro-(Gly)4 desulfato-Tyr63'-hirugen) complexes of human alpha-thrombin have been determined and refined at 2.2 A resolution to crystallographic R-factors of 0.167 and 0.163, respectively. The binding of hirugen to thrombin is similar to that of the binding of the C-terminal dodecapeptide of hirudin, including that of the terminal 3(10) helical turn. The sulfato Tyr63', which, as a result of sulfation, increases the binding affinity by an order of magnitude, is involved in an extended hydrogen bonding network utilizing all three sulfato oxygen atoms. The hirugen-thrombin complex is the first thrombin structure determined to have an unobstructed active site; this site is practically identical in positioning of catalytic residues and in its hydrogen bonding pattern with that of other serine proteinases. Hirulog 1, which is a poor thrombin substrate, is cleaved at the Arg3'-Pro4' bond in the crystal structure. The Arg3' of hirulog 1 occupies the specificity site, the D-Phe-Pro-Arg tripeptide is positioned like that of D-Phe-Pro-Arg chloromethylketone in the active site and the Pro4'(Gly)4 spacer to hirugen is disordered in the structure, as is the 3(10) turn of hirugen. The latter must be related to the simultaneous absence both of sulfation and of the last residue of hirudin (Gln65'). In addition, the autolysis loop of thrombin (Lys145-Gly150) is disordered in both structures. Changes in circular dichroism upon hirugen binding are therefore most likely the result of the flexibility associated with this loop.
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| ==About this Structure== | | ==About this Structure== |
| 2HGT is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. The following page contains interesting information on the relation of 2HGT with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb25_1.html Thrombin]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HGT OCA]. | | 2HGT is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. The following page contains interesting information on the relation of 2HGT with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb25_1.html Thrombin]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HGT OCA]. |
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| ==Reference==
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| Structure of the hirugen and hirulog 1 complexes of alpha-thrombin., Skrzypczak-Jankun E, Carperos VE, Ravichandran KG, Tulinsky A, Westbrook M, Maraganore JM, J Mol Biol. 1991 Oct 20;221(4):1379-93. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/1942057 1942057]
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| [[Category: Homo sapiens]] | | [[Category: Homo sapiens]] |
| [[Category: Protein complex]] | | [[Category: Protein complex]] |
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| [[Category: Carperos, V.]] | | [[Category: Carperos, V.]] |
| [[Category: Tulinsky, A.]] | | [[Category: Tulinsky, A.]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 06:16:42 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jun 26 18:18:26 2008'' |
