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R Noack

Publications and source records attributed to R Noack.

At least 91 records · Page 5Linked to original sources
PubMed1976

[Changes in the nutritive physiological value of proteins modified by dialdehyde starch].

The reaction of dialdehyde starch with the proteins of certain model protein texturates produces changes in the nutrition physiological quality of the proteins. Under the experimental conditions chosen, these changes were barely or not at all detectable by amino-acid analysis. On using the technique of aminoacid liberation under in vitro conditions, these changes were evidenced only for lysine and arginine. The determination of the lysine availability, however, testifies to a reversible or irreversible change of lysine which reduces significantly the PER values (animal experiments) of protein texturates treated with 100% oxidized dialdehyde starch. The differences between the NPU values were but insignificant. In spite of the detectable change in protein quality, the quality of the model protein texturates tested still satisfies the criteria for proteins with a composition which is favourable from the viewpoint of nutrition physiology.

Amino Acids↗
PubMed1976

[Nutritional study of field bean protein isolate and of spun field bean protein-casein fibers].

The amino acid composition of the different field bean protein isolates shows a good correspondence. In relation to casein the content of the whole essential amino acids is low. In the first line the low content of methionine and cystine limits the biological value of this proteins. The content of lysine is relatively high. The enzymatic in vitro-hydrolysis results in a corresponding availability of the amino acids between the field bean proteins and casein. The digestibility is very good, the biological value with less than 50 relatively low. Apart from the low content of the sulphur containing amino acids the amino acid composition of the spun field bean protein/casein(I:I) fibers corresponds with the calculated value; the enzymatic availability of the fibers is also comparable with casein. The digestibility in the nitrogen balance test is very good and the biological value of the fiber corresponds with that of casein.

Amino Acids↗
PubMed1975

[Digestion and resorption of proteins].

A survey is given of the ultrastructure of the intestinal epithelial cell, especially of its lumenward membrane. Special attention is paid to the peptidases which are located in the ciliated border and within the cell. The authors deal with the purification of the membrane-bound aminopeptidase which is of importance in splitting dietary peptides and illustrate its specificity by the cleavage of casein. The amino acids which are liberated by peptide splitting have in part aminopeptidase-inhibiting properties. The possible digestion physiological consequences are discussed. In vitro experiments were performed to investigate the composition of the content of the distal part of the small intestine of the rat with regard to its possible dependence on the composition of various dietary proteins. The composition of the peptides of the intestinal content is essentially undependent of the amino-acid composition of the diet. There is no enrichment of certain amino acids. The importance of the resorption of the peptides is also evidenced by resorption studies in which enzymatic hydrolysates of proteins (i.e. peptide mixtures) were confronted with a free amino-acid mixture of the same over-all composition. Taking glycyl-glycine-glycine as a model, the authors demonstrate that, in determined ranges of concentration, tripeptides may in part be resorbed without degradation. Finally, the importance of peptide resorption is evaluated and conclusions are drawn as to further studies on the physiology and physiopathology of digestion.

Amino Acids↗
PubMed1966

Proteolytic and peptidase activities of the jejunum and ileum of the rat during postnatal development.

1. Proteolytic (substrate nitrocasein), tripeptidase (substrate glycylglycylgly-cine) and aminopeptidase (substrate leucyl-beta-naphthylamide) activities were studied in homogenates of jejunal and ileal mucosa of 7-, 10-, 14-, 21-, 35- and 60-day-old rats. 2. Proteolytic activity was practically the same in jejunum of 7-, 10-, 14- and 21-day-old rats, but after day 21 a significant increase was observed. The activity of the ileum changed very little during postnatal development and was always higher than that of the jejunum. 3. Tripeptidase activity was low in the jejunum of 7- and 14-day-old rats, an increase was observed between day 14 and 21, but later no substantial changes were found. There were no changes in the ileum. The activity in the jejunum of 7- and 14-day-old rats was lower than in the ileum, but later the jejunum was more active than the ileum. 4. Aminopeptidase activity had a similar developmental pattern to tripeptidase activity. A low activity was found in the jejunum of 7- and 14-day-old rats, the maximum was in 21-day-old rats and then a decrease was observed, though values for 60-day-old rats were still higher than for 7- and 10-day-old rats. The activity in the ileum was practically the same in all age groups studied except in 14- and 21-day-old rats, where a transient peak was observed.

Aminopeptidases↗