1lu0

Atomic Resolution Structure of Squash Trypsin Inhibitor: Unexpected Metal Coordination

spinqualitylabelsall models 1lu0, resolution 1.03Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1lu0 is a 2 chain structure with sequence from Cucurbita maxima. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.03Å Ligands: GOL, MRD, SO4, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function ITR1_CUCMA Inhibits trypsin. Publication Abstract from PubMed CMTI-I, a small-protein trypsin inhibitor, has been crystallized as a 4:1 protein-zinc complex. The metal is coordinated in a symmetric tetrahedral fashion by glutamate/glutamic acid side chains. The structure was solved by direct methods in the absence of prior knowledge of the special position metal centre and refined with anisotropic displacement parameters using diffraction data extending to 1.03 A. In the final calculations, the main-chain atoms of low B(eq) values were refined without restraint control. The two molecules in the asymmetric unit have a conformation that is very similar to that reported earlier for CMTI-I in complex with trypsin, despite the Met8Leu mutation of the present variant. The only significant differences are in the enzyme-binding epitope (including the Arg5 residue) and in a higher mobility loop around Glu24. The present crystal structure contains organic solvent molecules (glycerol, MPD) that interact with the inhibitor molecules in an area that is at the enzyme-inhibitor interface in the CMTI-I-trypsin complex. A perfectly ordered residue (Ala18) has an unusual Ramachandran conformation as a result of geometrical strain introduced by the three disulfide bridges that clamp the protein fold. The results confirm deficiencies of some stereochemical restraints, such as peptide planarity or the N-C(alpha)-C angle, and suggest a link between their violations and hydrogen bonding. Atomic resolution structure of squash trypsin inhibitor: unexpected metal coordination.,Thaimattam R, Tykarska E, Bierzynski A, Sheldrick GM, Jaskolski M Acta Crystallogr D Biol Crystallogr. 2002 Sep;58(Pt 9):1448-61. Epub 2002, Aug 23. PMID:12198301 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Trypsin inhibitor 3D structures

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