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Proteolytic breakdown of kidney bean ( Phaseolus vulgaris ) storage proteins: Nutritional implications
Author(s) -
Sgarbieri Valdemiro C.,
Clarke M. W. Eileen,
Pusztai Arpad
Publication year - 1982
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740330911
Subject(s) - phaseolus , trichloroacetic acid , digestion (alchemy) , pepsin , stomach , biochemistry , kidney , food science , chemistry , caecum , glycoprotein , hydrolysis , in vivo , biology , storage protein , chromatography , enzyme , botany , medicine , endocrinology , microbiology and biotechnology , gene
Glycoprotein II, the major storage protein of the seeds of kidney bean ( Phaseolus vulgaris ), was largely resistant to hydrolysis by pure gut endopeptidases. However, the protein was extensively digested in vitro and nearly 90% of it became soluble in 5% trichloroacetic acid by treatments first with extracts of rat stomach followed by intestinal contents or alternatively first with pepsin, followed by pancreatin. Heat denaturation (100°C for 10 min) had no appreciable effect on the digestion. A similarly high extent (between 80 and 90%) and rate of digestion of pure Glycoprotein II was observed in vivo. However, intubation of pure Glycoprotein II into the stomach of previously fasted rats increased the production of insoluble intestinal secretions containing relatively large amounts of nitrogen. As this N passed into the caecum, it reduced both the apparent digestibility of Glycoprotein II and the net gain of N for the animal. Moreover, in the presence of a mixture of raw bean proteins in the stomach of rats the time taken to empty its content into the intestine was increased appreciably. Additionally, the toxic effects of the lectins in these mixtures, particularly on continuous feeding, were observed.