CBlock Clinical Studies

January 2, 1997

Characterization and functional properties of the alpha-amylase inhibitor (alpha-AI) from kidney bean (Phaseolus vulgaris) seeds.

Le Berre-Anton, V.; Bompard-Gilles, C.; Payan, F.; Rouge P.

Journal of Biochim Biophys Acta, vol. 1343
January 2, 1997

Alpha-amylase inhibitor (alpha-AI) from kidney bean (Phaseolus vulgaris L. cv Tendergreen) seeds has been purified to homogeneity by heat treatment in acidic medium, ammonium sulphate fractionation, chromatofocusing and gel filtration. Two isoforms, alpha-AI1 and alpha-AI1', of 43 kDa have been isolated which differ form each other by their isoelectric points and neutral sugar contents. The major isoform alpha-AI1 inihibited human and porcine pancreatic bacterial and fungal origins. As shown on the Lineweaver-Burk plots, the nature of the inhibition is explained by a mixed non-competitive inhibition mechanism. Alpha-AI1 formed a 1:2 stoichiometric complex with PPA which showed an optimum pH of 4.5 at 30 degrees C. Owing tot he low optimum pH found for alpha-AI activity, inhibitor-containing diets such as beans or transgenic plants expressing alpha-AI should be devoid of any harmful effect on human health.