1pbi
CRYSTAL STRUCTURE OF A BOWMAN-BIRK INHIBITOR FROM PEA SEEDS
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| , resolution 2.70Å | |||||||
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| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
The 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.
About this StructureAbout this Structure
1PBI is a Single protein structure of sequence from Pisum sativum. Full crystallographic information is available from OCA.
ReferenceReference
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
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