Purification and characterization of a glycoprotein α-amylase inhibitor from tepary bean seeds ( Phaseolus acutifolius A. Gray)

• Published in: Journal of plant physiology 1996, Vol.149 (6), p.650-656
• Main Authors: Blanco-Labra, A., Sandoval-Cardoso, L., Mendiola-Olaya, E., Valdés-Rodríguez, S., López, M.G.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; enzyme inhibitors; Enzymes; Fundamental and applied biological sciences. Psychology; Generalities. Disease free stocks; insect resistance; Metabolism; Phaseolus acutifolius; Phytopathology. Animal pests. Plant and forest protection; plant defense mechanism; Plant physiology and development; tepary beans; α-amylase inhibitors
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/S0176-1617(96)80087-3

An α-amylase inhibitor was extracted and purified from tepary bean seeds. It is a 37,700 u (Da) glycoprotein determined by electrophoresis. The carbohydrate moiety (17%), determined by gas chromatography-mass spectrometry, consisted mainly of glucose and mannose, with small quantities of 2-acetamide-2-deoxy-glucose, acetyl-xylose, and xylose. This inhibitor is similar in several characteristics to previous a-amylase inhibitors studied in other bean seeds, including its molecular mass and its isoelectric point (4.7). The specificity toward different insect amylases was particulary high for the amylases from two bruchids, which are important pests to common beans ( Z. subfasciatus and C. maculatus). This provides an interesting possibility for increasing resistance in common beans to attack by these pests. Its thermal stability was low even at temperatures as low as 60 °C.