1pbi
CRYSTAL STRUCTURE OF A BOWMAN-BIRK INHIBITOR FROM PEA SEEDS
Structural highlights
FunctionIBBB_PEA Inhibitor of trypsin and of chymotrypsin. May function as a natural phytochemical defense against predators. 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 PubMedThe trypsin/chymotrypsin inhibitors from winter pea seeds (PsTI) are members of the Bowman-Birk protease inhibitor (BBPI) family. The crystal structure of the isoform PsTI-IVb was determined by molecular replacement at 2.7 A resolution using the X-ray co-ordinates of the soybean inhibitor as a search model. The inhibitor crystallized with a nearly perfect 2-fold symmetric dimer in the asymmetric unit. Although the overall structure is very similar to that seen in other BBPIs, there are notable new structural features. Unlike the previously reported X-ray structures of BBPIs, the structure of PsTI-IVb includes the C-terminal segment of the molecule. The C-terminal tail of each subunit is partly beta-stranded and interacts with the 2-fold symmetry-related subunit, forming a beta-sheet with strands A and B of this subunit. The dimer is mainly stabilized by a large internal hydrogen-bonded network surrounded by two hydrophobic links. Fluorescence anisotropy decay measurements show that residues Tyr59 and Tyr43 are mobile in the picosecond time scale with a large amplitude. The fluorescence study and a molecular model of the simultaneous binding of PsTI-IVb to porcine trypsin and bovine chymotrypsin are compatible only with a monomeric state of the functional molecule in solution. Dimeric crystal structure of a Bowman-Birk protease inhibitor from pea seeds.,Li de la Sierra I, Quillien L, Flecker P, Gueguen J, Brunie S J Mol Biol. 1999 Jan 22;285(3):1195-207. PMID:9887273[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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