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La fermentation des ensilages comme procédé de conservation est pratiqué depuis des siècles et connaît un regain de popularité. Les modifications biochimiques et physiques qui se produisent à la fermentation revêtent à la fois une importance économique et nutritionnelle. La conversion de l'azote protéique en azote non-protéique peut atteindre un niveau tel que des ajouts de protéines s'avèrent quelquefois nécessaires. Notre étude a pour but de déterminer les changements dans chacune des différentes fractions (N total, N soluble, N-amino libre, etc.) durant la fermentation de luzerne hachée. Des silos de laboratoire (tubes de PVC, 25 x 7.6 cm) ont été …
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A partir de l'hydrolysat par pronase-P de la K-Caseiine, une fraction de glycopeptides est isolée qui contient 70-80% d'hydrate de carbone. Après pyridination de cette fraction, environ la moitié de ses résidüs aminoacyles se retrouve sous forme de dérivés DN Pyr, parmi lesquels on identifie celui de tous ses acides aminés, la thréonine exceptée. Il est suggéré que la partie peptidique de ces glycopeptides est composée en moyenne de deux résidus aminoacyles, et que la thréonine, lorsqu'elle y figure, y occupe la position C-terminale ou quasi C-Terminale.
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An apparatus has been designed and constructed for the fractionation of proteins on a preparatory scale. The apparatus which has a column capacity of approximately 120 mg is simple in construction and in operation. The zones that emerge from the column during electrophoresis are recovered continuously by means of a fraction collector.
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Starch-gel electrophoretic analysis of the water soluble proteins of pork muscle showed the presence of at least nineteen different components. The fractionation of the water extract by means of acetone precipitation and column chromatography (carboxy-methyl cellulose and Sephadex G-75) led to the isolation of a protein component which was shown by starch-gel electrophoresis and ultra-centrifugation to be homogeneous. The protein had a molecular weight of about 15,500, and the C-terminal amino acid was serine. It showed no esterase or proteolytic activity.
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K-casein prepared by Zittle's method was hydrolyzed with Pronase P and the resultant hydrolysate was fractionated by use of Dowex 50 and Dowex 1. Paper electrophoresis and thin-layer electrophoresis were used to follow the fractionation process. A carbohydrate-rich macropeptide has been isolated and its sialec acid, hexosamine and hexose contents have been determined. The macropeptide carries a negative charge at pH 5.2.
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Peas have been cooked in water containing radioactive calcium and the movement of calcium ions into the cotyledons has been followed by autoradiographic techniques. Peas of good cooking quality absorbed more calcium than did good cooking peas. The absorbed calcium was concentrated in the peripheral region of the cotyledons. The addition of ammonium citrate to the cooking water reduced the uptake of calcium ions by the peas. Results will be presented that suggest that the characteristic of the pectin in the pea may play a more important role in determining the cookability of peas than does the phytic acid content …
