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1dhk
From Proteopedia
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| , resolution 1.85Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , , , | ||||||
| Activity: | Alpha-amylase, with EC number 3.2.1.1 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
STRUCTURE OF PORCINE PANCREATIC ALPHA-AMYLASE
Overview
BACKGROUND: alpha-Amylases catalyze the hydrolysis of glycosidic linkages in starch and other related polysaccharides. The alpha-amylase inhibitor (alpha-Al) from the bean Phaseolus vulgaris belongs to a family of plant defence proteins and is a potent inhibitor of mammalian alpha-amylases. The structure of pig pancreatic alpha-amylase (PPA) in complex with both a carbohydrate inhibitor (acarbose) and a proteinaceous inhibitor (Tendamistat) is known, but the catalytic mechanism is poorly understood. RESULTS: The crystal structure of pig pancreatic alpha-amylase complexed with alpha-Al was refined to 1.85 A resolution. It reveals that in complex with PPA, the inhibitor has the typical dimer structure common to legume lectins. Two hairpin loops extending out from the jellyroll fold of a monomer interact directly with the active site region of the enzyme molecule, with the inhibitor molecule filling the whole substrate-docking region of the PPA. The inhibitor makes substrate-mimetic interactions with binding subsites of the enzyme and targets catalytic residues in the active site. Binding of inhibitor induces structural changes at the active site of the enzyme. CONCLUSIONS: The present analysis reveals that there are extensive interactions between the inhibitor and residues that are highly conserved in the active site of alpha-amylases; alpha-Al1 inactivates PPA through elaborate blockage of substrate-binding sites. It provides a basis to design peptide analogue inhibitors. alpha-Amylase inhibition is of interest from several points of view, for example the treatment of diabetes and for crop protection.
About this Structure
1DHK is a Protein complex structure of sequences from Phaseolus vulgaris and Sus scrofa. Full crystallographic information is available from OCA.
Reference
Substrate mimicry in the active center of a mammalian alpha-amylase: structural analysis of an enzyme-inhibitor complex., Bompard-Gilles C, Rousseau P, Rouge P, Payan F, Structure. 1996 Dec 15;4(12):1441-52. PMID:8994970
Page seeded by OCA on Sun Mar 30 19:41:36 2008
