2qyi | pdb_00002qyi

Crystal structure of a binary complex between an engineered trypsin inhibitor and Bovine trypsin

spinqualitylabelsall models 2qyi, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2qyi is a 4 chain structure with sequence from Bovin and Dolichos tetragonolobus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, NI Related: 1eyl, 1fmz, 1xg6 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [ICW3_PSOTE] Inhibits alpha-chymotrypsin at the molar ratio of 1:2 in state of 1:1. 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 PubMed Change in specificity, caused by the mutations at P1 site, of the serine protease inhibitors of different families is reported in the literature, but Kunitz (STI) family inhibitors are almost unexplored in this regard. In this paper, we present the crystal structure of a P1 variant of winged bean chymotrypsin inhibitor (WCI) belonging to Kunitz (STI) family, supplemented by biochemical, phylogenetic and docking studies on the mutant. A single mutation (Leu-->Arg) at P1 converted WCI to a strong inhibitor of trypsin with an association constant of 4.8x10(10) M(-1) which is comparable to other potent trypsin inhibitors of the family. The crystal structure (2.15 A) of this mutant (L65R) shows that its reactive site loop conformation deviates from that of WCI and adopts a structure similar to that of Erythrina caffra trypsin inhibitor (ETI) belonging to the same family. Mutation induced structural changes have also been propagated in a concerted manner to the neighboring conserved scaffolding residue Asn14, such that the side chain of this residue took an orientation similar to that of ETI and optimized the hydrogen bonds with the loop residues. While docking studies provide information about the accommodation of non-specific residues in the active site groove of trypsin, the basis of the directional alteration of the reactive site loop conformation has been understood through sequence analysis and related phylogenetic studies. Single mutation at P1 of a chymotrypsin inhibitor changes it to a trypsin inhibitor: X-ray structural (2.15 A) and biochemical basis.,Khamrui S, Dasgupta J, Dattagupta JK, Sen U Biochim Biophys Acta. 2005 Aug 31;1752(1):65-72. PMID:16081330 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Chymotrypsin Inhibitor Trypsin

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