2lqx

Publication Abstract from PubMed

A new peptide trypsin inhibitor named BWI-2c was obtained from buckwheat (Fagopyrum esculentum) seeds by sequential affinity, ion exchange and reversed phase chromatography. The peptide was sequenced and found to contain 41 amino acid residues, with four cysteines involved in two intramolecular disulfide bonds. Recombinant BWI-2c identical to the natural peptide was produced in Escherichia coli in a form of a cleavable fusion with thioredoxin. The 3D structure of the peptide in solution was determined by NMR spectroscopy revealing two antiparallel alpha-helices stapled by disulfide bonds. Together with trypsin inhibitor from veronica (Veronica hederifolia; VhTI), BWI-2c represents a new family of protease inhibitors with the unusual alpha-helical hairpin fold. The linker sequence between the helices represents the so-called trypsin inhibitory loop responsible for direct binding to the active site of the enzyme that cleaves BWI-2c at the functionally important residue arginine-19. The inhibition constant was determined for BWI-2c against trypsin (1.7x10-10 M), and the peptide was tested on other enzymes including those from various insect digestive systems revealing high selectivity to trypsin-like proteases. Structural similarity shared by BWI-2c, VhTI and several other plant defense peptides leads to the acknowledgement of a new widespread family of plant peptides termed alpha-hairpinins.

Buckwheat trypsin inhibitor with helical hairpin structure belongs to a new family of plant defense peptides.,Oparin PB, Mineev KS, Dunaevsky YE, Arseniev AS, Belozersky MA, Grishin EV, Egorov TA, Vassilevski AA Biochem J. 2012 May 22. PMID:22612157^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.