A new method for the fractionation of dough made from wheat flour is described. The method does not involve the use of diluents or extractants and consists simply of ultracentrifugation of the dough. With this method dough is resolved into from five to seven discrete layers, depending on the dough treatment. A study of the fractionation of doughs made from seven Australian flours is described together with the physical and chemical composition of the various layers.
SummaryCrude tetanus toxin and toxoid were prepared by methanol precipitation. The toxin was purified by a combination of TEAE·cellulose and Sephadex G·200 chromatography at pH values less than 6· o. The toxoid was purified by DEAE· cellulose at approximately neutral pH values. The nature and amount of amino acids of the culture medium which had condensed with the tetanus toxoid proteins during detoxification with formaldehyde was determined.
Tetanus toxin has been extracted from culture filtrates by a single, cold methanol precipitation, followed by gradient elution on DEAE-cellulose. Immunoelectrophoretic evidence indicated that most of the bacterial protein was precipitated by the methanol. Selection of the toxin elution peak gave a product having only one immunoelectrophoresis precipitin line yet containing 50--60% of the Lf units applied to the column. The toxicity of this product was comparable to that found by other workers, using other methods of preparation. Sedimentation values of the concentrated pure toxin indicated heterogeneity in molecular aggregation and under conditions used no 4 S material could be found. Amino acid analysis of the tetanus protein is also reported.
SummaryDoughs made from Australian wheat flours were fractionated by ultracentrifugation. The disulphide and sulphydryl contents of the fractions were determined polarographically. A low molecular weight, sulphydryl-containing fraction was found in doughs made from poor quality flours.Up to 26% of the sulphydryl groups originally present in the flours disappeared during dough formation. Doughs mixed in the presence of air or iodate showed a rapid initial, and subsequent more gradual loss of sulphydryl groups as mixing progressed, or as the concentration of iodate increased. The sulphydryl groups of the soluble components of dough were more labile during overmixing, and in the presence of iodate and N -ethyl maleimide than were the sulphydryl groups of the gluten complex.
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