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Isolation and characterisation of wheat flour proteins . II. .—effects of urea and N ‐ethylmaleimide on the behaviour of wheat proteins during extraction and fractionation
Author(s) -
Jankiewicz M.,
Pomeranz Y.
Publication year - 1965
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.2740161104
Subject(s) - chemistry , sephadex , chromatography , urea , fractionation , ultracentrifuge , extraction (chemistry) , ultrafiltration (renal) , sucrose , biochemistry , enzyme
Proteins were extracted from wheat flour with seven different extractants. Extraction with 3·0 M‐urea at pH 7·0 and at 4° solubilised practically all the proteinaceous material in wheat flour. Extracted proteins were dialysed against 0·005 M‐acetate buffer pH 4·1, concentrated by ultrafiltration and lyophylised. Proteins were fractionated in acetate buffer pH 4·1 by sucrose gradient ultracentrifugation or on Sephadex G‐100, and the viscosity of Sephadex G‐100 eluates was determined. Adding N ‐ethylmaleimide alone, but not in the presence of urea, reduced the yields of proteins extracted in a two‐step procedure and increased the relative amounts of proteins of high molecular weight. Adding urea resulted in distinct separation of intermediate‐sized proteins into two fractions. Proteins were fractionated on Sephadex G‐100 into up to eight fractions, varying in molecular weight, and they were rechromatographed on Sephadex G‐100 or G‐200. The results indicated aggregation and disaggregation phenomena, and heterogeneity of protein fractions under conditions used.