1h8d: Difference between revisions
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==Overview== | ==Overview== | ||
X-ray crystallographic studies of human alpha-thrombin with a novel, synthetic inhibitor, an acyl (alpha-aminoalkyl)phosphonate, reveal the, existence of a pentacovalent phosphorus intermediate state. Crystal, structures of the complex of alpha-thrombin with the phosphonate compound, were determined independently using crystals of different ages. The first, structure, solved from a crystal less than seven days old, showed a, pentacoordinated phosphorus moiety. The second structure, determined from, a crystal that was 12 weeks old, showed a tetracoordinated phosphorus, moiety. In the first structure, a water molecule, made nucleophilic by, coordination to His57 of alpha-thrombin, is bonded to the pentacoordinated, phosphorus atom. Its position is approximately equivalent to that occupied, .. | X-ray crystallographic studies of human alpha-thrombin with a novel, synthetic inhibitor, an acyl (alpha-aminoalkyl)phosphonate, reveal the, existence of a pentacovalent phosphorus intermediate state. Crystal, structures of the complex of alpha-thrombin with the phosphonate compound, were determined independently using crystals of different ages. The first, structure, solved from a crystal less than seven days old, showed a, pentacoordinated phosphorus moiety. The second structure, determined from, a crystal that was 12 weeks old, showed a tetracoordinated phosphorus, moiety. In the first structure, a water molecule, made nucleophilic by, coordination to His57 of alpha-thrombin, is bonded to the pentacoordinated, phosphorus atom. Its position is approximately equivalent to that occupied, by the water molecule responsible for hydrolytic deacylation during normal, hydrolysis. The pentacoordinated phosphorus adduct collapses to give the, expected pseudo tetrahedral complex, where the phosphorus atom is, covalently bonded to Ser195 O(gamma). The crystallographic data presented, here therefore suggest that the covalent bond formed between the, inhibitor's phosphorus atom and O(gamma) of Ser195 proceeds via an, addition-elimination mechanism, which involves the formation of a, pentacoordinate intermediate. | ||
==About this Structure== | ==About this Structure== | ||
1H8D is a | 1H8D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Hirudo_medicinalis Hirudo medicinalis] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with PHW as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Thrombin Thrombin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.5 3.4.21.5] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1H8D OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: serine protease]] | [[Category: serine protease]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 13:56:34 2007'' | ||
