Amino acid sequence of a crystalline seed albumin (winged bean albumin-1) from Psophocarpus tetragonolobus (L.) DC. Sequence similarity with Kunitz-type seed inhibitors and 7S storage globulins.
The complete amino acid sequence of winged bean albumin-1 (WBA-1) of Psophocarpus tetragonolobus (L.) DC has been determined. The protein consists of a single polypeptide chain of 175 amino acid residues, with one disulfide bond, corresponding to a molecular mass of 19333 Da. WBA-1 was found to be homologous with the Kunitz-type seed trypsin inhibitors. The similarity between WBA-1 and the trypsin inhibitors from soybean and winged bean was 38% and 28%, respectively; similarity was most marked in the C-terminal third of the sequence with identities of 47% and 37%, respectively. Significant similarity was found also between the 2S Kunitz-type proteins and the carboxy-terminal region of the 7S storage globulins, suggesting that these two groups of proteins are related and may have evolved from a common ancestral precursor. Circular dichroism measurements suggest a high content of beta sheet (52%) while secondary structure predictions based on amino acid sequence indicate a similar content and distribution of beta sheet to that found for soybean trypsin inhibitor by X-ray diffraction studies.
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Commonwealth Scientific and Industrial Research Organisation, Division of Biotechnology, Parkville, Melbourne, Australia.
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De Jersey
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D000418:Albumins; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D005091:Exons; D005916:Globulins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D010447:Peptide Hydrolases; D010940:Plant Proteins / Q000302:isolation & purification; D055314:Seed Storage Proteins; D012639:Seeds / Q000032:analysis*; D012689:Sequence Homology, Nucleic Acid; D030262:Soybean Proteins; D014360:Trypsin Inhibitor, Kunitz Soybean; D014361:Trypsin Inhibitors
D000418:Albumins; D052179:Antigens, Plant; D005916:Globulins; D010446:Peptide Fragments; D010940:Plant Proteins; D055314:Seed Storage Proteins; D030262:Soybean Proteins; D014361:Trypsin Inhibitors; C059657:WBA-1 protein, Psophocarpus tetragonolobus; C013894:beta-conglycinin protein, Glycine max; D014360:Trypsin Inhibitor, Kunitz Soybean; D010447:Peptide Hydrolases