2f91

1.2A resolution structure of a crayfish trypsin complexed with a peptide inhibitor, SGTI

spinqualitylabelsall models 2f91, resolution 1.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2f91 is a 2 chain structure with sequence from Astacus leptodactylus and Schistocerca gregaria. This structure supersedes the now removed PDB entry 1yr4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.2Å Ligands: CD, CL Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q52V24_ASTLP 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 Atomic resolution (<or=1.2 A) serine protease intermediate structures revealed that the strength of the hydrogen bonds between the enzyme and the substrate changed during catalysis. The well-conserved hydrogen bonds of antiparallel beta-sheet between the enzyme and the substrate become significantly shorter in the transition from a Michaelis complex analogue (Pontastacus leptodactylus (narrow-fingered crayfish) trypsin (CFT) in complex with Schistocerca gregaria (desert locust) trypsin inhibitor (SGTI) at 1.2 A resolution) to an acyl-enzyme intermediate (N-acetyl-Asn-Pro-Ile acyl-enzyme intermediate of porcine pancreatic elastase at 0.95 A resolution) presumably synchronously with the nucleophilic attack on the carbonyl carbon atom of the scissile peptide bond. This is interpreted as an active mechanism that utilizes the energy released from the stronger hydrogen bonds to overcome the energetic barrier of the nucleophilic attack by the hydroxyl group of the catalytic serine. In the CFT:SGTI complex this hydrogen bond shortening may be hindered by the 27I-32I disulfide bridge and Asn-15I of SGTI. The position of the catalytic histidine changes slightly as it adapts to the different nucleophilic attacker during the transition from the Michaelis complex to the acyl-enzyme state, and simultaneously its interaction with Asp-102 and Ser-214 becomes stronger. The oxyanion hole hydrogen bonds provide additional stabilization for acyl-ester bond in the acyl-enzyme than for scissile peptide bond of the Michaelis complex. Significant deviation from planarity is not observed in the reactive bonds of either the Michaelis complex or the acyl-enzyme. In the Michaelis complex the electron distribution of the carbonyl bond is distorted toward the oxygen atom compared to other peptide bonds in the structure, which indicates the polarization effect of the oxyanion hole. Enzyme:substrate hydrogen bond shortening during the acylation phase of serine protease catalysis.,Fodor K, Harmat V, Neutze R, Szilagyi L, Graf L, Katona G Biochemistry. 2006 Feb 21;45(7):2114-21. PMID:16475800 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Trypsin 3D structures

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