1an1

LEECH-DERIVED TRYPTASE INHIBITOR/TRYPSIN COMPLEX

spinqualitylabelsall models 1an1, resolution 2.03Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1an1 is a 2 chain structure with sequence from Hirudo medicinalis and Sus scrofa. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.03Å Ligands: CA, DAS Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TRYP_PIG 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 BACKGROUND: Tryptase is a trypsin-like serine proteinase stored in the cytoplasmic granules of mast cells, which has been implicated in a number of mast cell related disorders such as asthma and rheumatoid arthritis. Unlike almost all other serine proteinases, tryptase is fully active in plasma and in the extracellular space, as there are no known natural inhibitors of tryptase in humans. Leech-derived tryptase inhibitor (LDTI), a protein of 46 amino acids, is the first molecule found to bind tightly to and specifically inhibit human tryptase in the nanomolar range. LDTI also inhibits trypsin and chymotrypsin with similar affinities. The structure of LDTI in complex with an inhibited proteinase could be used as a template for the development of low molecular weight tryptase inhibitors. RESULTS: The crystal structure of the complex between trypsin and LDTI was solved at 2.0 A resolution and a model of the LDTI-tryptase complex was created, based on this X-ray structure. LDTI has a very similar fold to the third domain of the turkey ovomucoid inhibitor. LDTI interacts with trypsin almost exclusively through its binding loop (residues 3-10) and especially through the sidechain of the specificity residue Lys8. Our modeling studies indicate that these interactions are maintained in the LDTI-tryptase complex. CONCLUSIONS: The insertion of nine residues after residue 174 in tryptase, relative to trypsin and chymotrypsin, prevents inhibition by other trypsin inhibitors and is certainly responsible for the higher specificity of tryptase relative to trypsin. In LDTI, the disulfide bond between residues 4 and 25 causes a sharp turn from the binding loop towards the N terminus, holding the N terminus away from the 174 loop of tryptase. Structure of the complex of leech-derived tryptase inhibitor (LDTI) with trypsin and modeling of the LDTI-tryptase system.,Di Marco S, Priestle JP Structure. 1997 Nov 15;5(11):1465-74. PMID:9384562 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Trypsin 3D structures Tryptase inhibitor

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