Amino acid sequence and disulfide bridges of affinity purified Kunitz-type chymotrypsin inhibitor from winged bean seed (Psophocarpus tetragonolobus (L.) DC).
The primary sequence of the affinity purified chymotrypsin inhibitor, WBCI, isolated from the albumin fraction of Psophocarpus tetragonolobus (L.) DC cv. UPS-122 seed was determined. The inhibitor consisted of a single polypeptide chain of 183 amino acids (Mr 20285) and the four half-cystine residues in the molecule formed two intramolecular disulfide bridges equivalent to those in other Kunitz-type seed inhibitors. The sequence of this chymotrypsin inhibitor was identical to that of chymotrypsin inhibitor-3 from cultivar UPS-31 and it showed about 50% sequence similarity to the winged bean acidic (WBTI-2, pI 5.1) and basic (WBTI-1, pI 8.9) trypsin inhibitors. Sequence similarities to other Kunitz-type seed inhibitors are discussed.
Kortt
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CSIRO, Division of Biomolecular Engineering, Parkville Laboratory, Victoria, Australia.
Burns
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Strike
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002846:Chromatography, Affinity; D004220:Disulfides / Q000032:analysis; D007887:Fabaceae / Q000032:analysis*; D008969:Molecular Sequence Data; D010940:Plant Proteins; D010946:Plants, Medicinal; D012689:Sequence Homology, Nucleic Acid; D014361:Trypsin Inhibitors / Q000737:chemistry*
D000596:Amino Acids; D004220:Disulfides; D010940:Plant Proteins; D014361:Trypsin Inhibitors; C440588:WCI protein, Psophocarpus tetragonolobus