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The in vitro hydrolysis of leaf proteins. II .—The action of papain on protein concentrates extracted from leaves of different species
Author(s) -
Byers M.
Publication year - 1967
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.2740180110
Subject(s) - papain , hydrolysis , in vitro , in vivo , cytoplasm , biochemistry , digestion (alchemy) , biology , fraction (chemistry) , chemistry , chromatography , botany , enzyme , microbiology and biotechnology
The in vitro digestion by papain of protein concentrates extracted from 14 different species of leaves is described. The extent of hydrolysis varies with species and is probably influenced by preparative technique. The effect of leaf age is less certain: most proteins made by the current standard procedure from any one species, at all stages of growth, have similar digestibilities, but the digestibility of some preparations from mature leaves is less in vitro , but more in vivo , than of preparations from young leaves. The hydrolysis of some fractionated proteins, prepared by controlled heating of leaf extracts, is also described. For all the species examined the ‘chloroplastic’ fraction is digested less, and the ‘cytoplasmic’ fraction more, than the corresponding whole protein: these results agree with those previously obtained in vivo. Differences in the N contents and in vitro digestibility of laboratory‐prepared fractions and those made on a large scale are discussed. Simulated whole protein, made by combining ‘chloroplastic’ and ‘cytoplasmic’ fractions in the correct proportions, is not hydrolysed to the same extent as the corresponding whole concentrate. The percentages of ‘chloroplastic’ and ‘cytoplasmic’ protein, made by the method described here, varies with species, but the ratio seems not to alter as the leaf matures; this could explain the consistent in vitro results usually obtained with recent preparations, irrespective of leaf age. It is suggested that protein digestibility could be assessed rapidly by the method described here as a preliminary to the more thorough, but slower, in vivo tests.