Dietary regulation of intestinal transport of the dipeptide carnosine

1988 ◽  
Vol 255 (2) ◽  
pp. G143-G150 ◽  
Author(s):  
R. P. Ferraris ◽  
J. Diamond ◽  
W. W. Kwan
Keyword(s):  
Amino Acids ◽  
Cell Surface ◽  
Dietary Protein ◽  
Free Amino Acids ◽  
Free Amino ◽  
Intestinal Transport ◽  
Dietary Regulation ◽  
Dietary Protein Level ◽  
Low Protein ◽  
Hydrolysis Of

Uptake of the dipeptide L-carnosine was measured in everted intestinal sleeves of mice whose dietary protein level or else proportion of protein in the form of free amino acids was varied experimentally. Carnosine uptake was highest in the jejunum, regardless of ration. Compared with a low-protein (18%) ration, a high-protein (72%) ration stimulated carnosine uptake by 30-70% in duodenum and jejunum (but not in ileum). This stimulation was observed even in the presence of peptidase inhibitors that inhibit cell surface hydrolysis of dipeptides. Measured carnosine hydrolysis was low or negligible. Carnosine uptake was the same in mice fed 54% unhydrolyzed casein, 54% partly hydrolyzed casein, and 54% free amino acids formulated so as to stimulate a complete hydrolysate of casein. Thus carnosine uptake is regulated by dietary levels of amino acids, peptides, and proteins, all of which seem equally effective at inducing carnosine transporters.

The effect of dietary protein quality on free amino acids in plasma, muscle and liver of growing chickens

1993 ◽  
Vol 57 (2) ◽  
pp. 309-318 ◽  
Author(s):  
I. Fernández-Figares ◽  
M. Lachica ◽  
L. Pérez ◽  
R. Nieto ◽  
J. F. Aguilera ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Dietary Protein ◽  
Free Amino Acids ◽  
Free Amino ◽  
Protein Quality ◽  
Sole Source ◽  
Metabolizable Energy ◽  
Low Protein ◽  
Protein Diets

AbstractFree amino acid (AA) levels in plasma, muscle and liver were measured in growing chickens given either high or low protein diets varying in quality. In experiment 1, they were force-fed once a day (09.00 h), for 4 days, at about 1·5 × M level, a nitrogen-free (NF) diet and then, on day 5, they were given either diet NF or isoenergetic (13·1 kj metabolizable energy (ME) per g dry matter (DM)) and isonitrogenous high protein diets (200 g crude protein (CP) per kg) based on casein (C), lupin (L), soya bean (SB), faba bean (FB), field pea (FP), vetch (V) or bitter vetch (B) as the sole source of protein. In experiment 2, chickens were force-fed twice a day (09.00 h and 18.00 h), for 3 days, at about 1·9 × M level, with four isoenergetic (13·1 k) ME per kg DM) and isonitrogenous low protein diets (120 g CP per kg) based on SB, FP, V or B as the sole source of protein. On days 5 (experiment 1) and 4 (experiment 2) samples of plasma, muscle and liver were taken for AA analysis over 3 to 4h after morning meal.In general, within experiments, no significant differences in AA concentrations in plasma, muscle or liver among diets were found. However, there was a qualitative but not a quantitative agreement between the AA abundance in tissues and the AA rank of dietary protein. Moreover, when pooling data from experiments 1 and 2, significant regressions were found between the levels of threonine, aspartic acid, glutamic acid, glycine and proline in plasma, of lysine, alanine, glutamic acid, glycine and proline in muscle or that of proline in liver and the corresponding amounts ingested with the different diets. Under the conditions of these experiments, however, it was not possible to establish conclusively a direct relationship between the level of free amino acids in tissues and dietary protein quality.

Availability of amino acids supplied by constant intravenous infusion of synthetic dipeptides in healthy man

1989 ◽  
Vol 76 (6) ◽  
pp. 643-648 ◽  
Author(s):  
S. Albers ◽  
J. Wernerman ◽  
P. Stehle ◽  
E. Vinnars ◽  
P. Fürst
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Metabolic Clearance ◽  
Amino Acid Solution ◽  
Appreciable Change ◽  
Total Body ◽  
Hydrolysis Of ◽  
Firm Evidence ◽  
Apparently Healthy

1. A commercial amino acid solution supplemented with two synthetic dipeptides, l-alanyl-l-glutamine (Ala-Gln) and glycyl-l-tyrosine (Gly-Tyr), or alternatively with isonitrogenous amounts of free alanine and glycine has been continuously infused over 4 h in six apparently healthy volunteers. 2. The infusion of the solutions was not accompanied by any side effects and the volunteers reported no complaints. 3. Infusion of the alanine- and glycine-supplemented control solution resulted in an increase of the concentration of these amino acids, while no appreciable change in free glutamine concentration was observed and free tyrosine revealed a steady decrease throughout the infusion. 4. Infusion of the peptide-supplemented solution resulted in a prompt equimolar liberation of the constituent free amino acids (glutamine, alanine, tyrosine and glycine), approaching steady state after about 30 min infusion, while only trace but stable concentrations of the two dipeptides were measured throughout the infusion. No peptides were detectable in urine. The findings suggest a nearly quantitative extracellular hydrolysis of the infused dipeptides and indicate a subsequent utilization of the liberated free amino acids. 5. The estimated metabolic clearance rates and total body plasma clearances were very similar for the two dipeptides (Ala-Gln 35.9 ± 9.5 ml min−1 kg−1 and 2.9 ± 0.9 1/min, respectively; Gly-Tyr 33.7 ± 9.5 ml min−1 kg−1 and 2.7 ± 0.9 1/min, respectively); thus there is little difference in the metabolic handling of these dipeptides. 6. The study provides firm evidence that the synthetic dipeptides Ala-Gln and Gly-Tyr are quantitatively hydrolysed and that these peptides can be used as a safe and efficient source of free glutamine and tyrosine as part of a commercial solution.

scholarly journals Isolation of Free Amino Acids via Enzymatic Hydrolysis of Tobacco-Derived F1 Protein

2018 ◽  
Vol 28 (4) ◽  
pp. 179-190
Author(s):  
Mehdi Ashraf-Khorassani ◽  
William M. Coleman ◽  
Michael F. Dube ◽  
Larry T. Taylor
Keyword(s):  
Amino Acids ◽  
Enzymatic Hydrolysis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Protein Concentration ◽  
Enzyme Concentration ◽  
Enzymatic Conversion ◽  
Reaction Conditions ◽  
Analytical Methodology ◽  
Hydrolysis Of

SummaryFree amino acids have been isolated via optimized enzymatic hydrolysis of F1 tobacco protein using two cationic resins (Amberlite IR120 and Dowex MAC-2). Optimized enzymatic conversions of the protein as a result of systematic variations in conditions (e.g., time, temperature, pH, enzyme type, enzyme concentration, anaerobic/aerobic environments, and protein concentration) employing commercially available enzymes, were consistently higher than 50% with qualitative amino acid arrays that were consistent with the known composition of tobacco F1 protein. Amberlite IR120 was shown to have a much higher efficiency and capacity for isolation of amino acids from standard solutions and from hydrolysate when compared with the results using Dowex MAC-2. Two columns packed with conditioned Amberlite IR120 (120 × 10 mm,12–15 g resin) and (200 × 25.4 mm, 60–65 g resin) were used to isolate two batches (2.5–3.0 mg and 13–15 mg) of free amino acids, respectively. A relatively inexpensive analytical methodology was developed for rapid analysis of the free amino acids contained within the enzyme hydrolysate. Commercially available enzymes, when employed in optimized reaction conditions, are very effective for enzymatic conversion of tobacco F1 protein to free amino acids.

Milk Protein Quantity and Quality in Low-Birth-Weight Infants: II. Effects on Selected Aliphatic Amino Acids in Plasma and Urine

PEDIATRICS ◽  
1977 ◽  
Vol 59 (3) ◽  
pp. 407-422 ◽  
Author(s):  
David K. Rassin ◽  
Gerald E. Gaull ◽  
Kirsti Heinonen ◽  
Niels C. R. Räihäa
Keyword(s):  
Amino Acids ◽  
Birth Weight ◽  
Low Birth Weight ◽  
Human Milk ◽  
Free Amino Acids ◽  
Free Amino ◽  
Plasma Concentrations ◽  
Low Birth Weight Infants ◽  
Low Protein ◽  
Protein Diets

The optimal quantity and quality of protein for low-birth-weight infants is undefined. In this study, 106 well, appropriate-for-gestational-age, low-birth-weight infants weighing 2,100 gm or less were divided into three gestational age groups and assigned randomly within each age group to one of five feeding regimens: pooled human milk; formula 1 (protein content, 1.5 gm/100 ml, 60 parts bovine whey proteins to 40 parts bovine caseins); formula 2 (3.0 gm/100 ml, 60:40); formula 3 (1.5 gm/100 ml, 18:82); and formula 4 (3.0 gm/100 ml, 18:82). The concentrations of the free amino acids in the plasma and urine of these infants were determined. The plasma concentrations of free amino acids were generally far greater in the infants fed the 3.0-gm/100 ml protein diets than they were in the infants fed pooled human milk. The plasma concentrations of free amino acids of the infants fed the 1.5-gm/100 ml protein diets were intermediate. In general, the concentrations of the free amino acids in the plasma of the infants fed the 3.0-gm/100 ml caseinpredominant formula (F4) were furthest from those fed pooled human milk. Glutamate showed the highest plasma amino acid concentrations in infants fed both the high- and low-protein casein-predominant formulas. This was true despite the fact that the intake of glutamate on the high-protein, whey-predominant formula was twice that on the low-protein, casein-predominant formula. The differences between groups in the essential amino acids in plasma were generally greater than those of the nonessential amino acids. The concentrations of amino acids in the urine tended to parallel those of the plasma.

scholarly journals The Effect of Fermentation with Kefir Grains on the Physicochemical and Antioxidant Properties of Beverages from Blue Lupin (Lupinus angustifolius L.) Seeds

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5791
Author(s):  
Łukasz Łopusiewicz ◽  
Emilia Drozłowska ◽  
Paulina Trocer ◽  
Paweł Kwiatkowski ◽  
Artur Bartkowiak ◽  
...  
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Microbial Population ◽  
Antioxidant Properties ◽  
Lupinus Angustifolius ◽  
Kefir Grains ◽  
Antioxidant Properties Of Beverages ◽  
Hydrolysis Of ◽  
Free Radicals Scavenging

Plant derived fermented beverages have recently gained consumers’ interest, particularly due to their intrinsic functional properties and presence of beneficial microorganisms. Three variants containing 5%, 10%, and 15% (w/w) of sweet blue lupin (Lupinus angustifolius L. cv. “Boregine”) seeds were inoculated with kefir grains and incubated at 25 °C for 24 h. After processing, beverages were stored in refrigerated conditions (6 °C) for 21 days. Changes in microbial population, pH, bioactive compounds (polyphenolics, flavonoids, ascorbic acid), reducing sugars, and free amino acids were estimated. Additionally, viscosity, firmness, color, and free radicals scavenging properties were determined. Results showed that lactic acid bacteria as well as yeast were capable of growing well in the lupin matrix without any supplementation. During the process of refrigeration, the viability of the microorganisms was over the recommended minimum level for kefir products. Hydrolysis of polysaccharides as well as increase of free amino acids was observed. As a result of fermentation, the beverages showed excellent DPPH, ABTS+·, ·OH, and O2− radicals scavenging activities with a potential when considering diseases associated with oxidative stress. This beverages could be used as a new, non-dairy vehicle for beneficial microflora consumption, especially by vegans and lactose-intolerant consumers.

Dipeptide utilization by starter streptococci

1977 ◽  
Vol 44 (2) ◽  
pp. 309-317 ◽  
Author(s):  
B. A. Law
Keyword(s):  
Amino Acids ◽  
Transport System ◽  
Free Amino Acids ◽  
Free Amino ◽  
Essential Amino Acids ◽  
Exponential Phase ◽  
Whole Cells ◽  
Streptococcus Cremoris ◽  
Defined Media ◽  
Hydrolysis Of

SummaryOf 8 strains ofStreptococcus cremoristested, 5 grew almost as well in defined media in which various essential amino acids were supplied in dipeptides as they did in media containing the equivalent free amino acids. The remainder grew poorly or not at all in the peptide-containing media. Growth of peptide-utilizing strains was inhibited by also including structurally-related dipeptides in the medium, presumably due to competition for uptake by transport system carriers. Both types of starters produced cell-free dipeptidases recoverable from the medium of exponential phase cultures. Addition of the partly-purified extracellular dipeptidases to dipeptidecontaining test media initiated growth in strains unable to use peptides.Str. lactisgrew in defined peptide media, but the further addition of structurally-related dipeptides did not inhibit growth, either bcause each dipeptide was transported by a specific carrier or because peptides were hydrolysed extracellularly. The presence of cell-bound extracellular dipeptidase was indicated by the hydrolysis of dipeptides with washed whole cells in buffer. This was not observed withStr. cremorisstrains.

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