Competition between Carnosine and other Peptides for Transport by Hamster Jejunum in Vitro

1974 ◽  
Vol 46 (6) ◽  
pp. 707-714 ◽  
Author(s):  
Jill M. Addison ◽  
D. M. Matthews ◽  
D. Burston
Keyword(s):  
Amino Acids ◽  
Intestinal Mucosa ◽  
Free Amino Acids ◽  
Free Amino ◽  
Common Mechanism ◽  
Uptake Mechanism ◽  
Mucosal Cells ◽  
Dipeptide Uptake

1. This paper reports the results of experiments on competition for transport by hamster jejunum in vitro between carnosine (β-alanyl-l-histidine) and other peptides and amino acids. Carnosine was chosen because this dipeptide is taken up intact with very little hydrolysis, which simplifies interpretation of the results. 2. Jejunal uptake of carnosine was inhibited by equimolar glycylglycine, glycylglycylglycine, glycylsarcosine, glycylproline, methionylmethionine and prolylhydroxy-proline but not by the equivalent free amino acids, or by a mixture of β-alanine and histidine. Inhibition of carnosine uptake by glycylproline was shown to be competitive. It is suggested that carnosine and the dipeptides inhibiting its uptake enter the mucosal cells by a common mechanism which is independent of the entry mechanisms for amino acids. Uptake of carnosine was not inhibited by N-acetylglycylglycine or by glycylglycine amide, suggesting that these substitutions prevent glycylglycine utilizing the dipeptide-uptake mechanism. 3. Carnosine uptake was not inhibited by equimolar lysyllysine or α-glutamylglutamic acid, nor did lysyllysine and α-glutamylglutamic acid affect uptake of each other. Though these results are compatible with the existence of multiple dipeptide-uptake systems in the intestinal mucosa, the evidence at present available is insufficient to permit any conclusion on this point.

scholarly journals Amino acid regulation of synthesis of ribonucleic acid and protein in the liver of rats

1971 ◽  
Vol 124 (2) ◽  
pp. 385-392 ◽  
Author(s):  
R. W. Wannemacher ◽  
C. F. Wannemacher ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Cellular Protein ◽  
Deficient Diet ◽  
Cellular Protein Content ◽  
Regulate Protein

Weanling (23-day-old) rats were fed on either a low-protein diet (6% casein) or a diet containing an adequate amount of protein (18% casein) for 28 days. Hepatic cells from animals fed on the deficient diet were characterized by markedly lower concentrations of protein and RNA in all cellular fractions as compared with cells from control rats. The bound rRNA fraction was decreased to the greatest degree, whereas the free ribosomal concentrations were only slightly less than in control animals. A good correlation was observed between the rate of hepatic protein synthesis in vivo and the cellular protein content of the liver. Rates of protein synthesis both in vivo and in vitro were directly correlated with the hepatic concentration of individual free amino acids that are essential for protein synthesis. The decreased protein-synthetic ability of the ribosomes from the liver of protein-deprived rats was related to a decrease in the number of active ribosomes and heavy polyribosomes. The lower ribosomal content of the hepatocytes was correlated with the decreased concentration of essential free amino acids. In the protein-deprived rats, the rate of accumulation of newly synthesized cytoplasmic rRNA was markedly decreased compared with control animals. From these results it was concluded that amino acids regulate protein synthesis (1) by affecting the number of ribosomes that actively synthesize protein and (2) by inhibiting the rate of synthesis of new ribosomes. Both of these processes may involve the synthesis of proteins with a rapid rate of turnover.

Correlation between osmoregulation and cell volume regulation

1987 ◽  
Vol 252 (4) ◽  
pp. R768-R773
Author(s):  
M. A. Lang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Free Amino Acids ◽  
Volume Regulation ◽  
Free Amino ◽  
Cell Volume Regulation

The euryhaline crab, Callinectes sapidus, behaves both as an osmoregulator when equilibrated in salines in the range of 800 mosM and below and an osmoconformer when equilibrated in salines above 800 mosM. There exists a close correlation between osmoregulation seen in the whole animal in vivo and cell volume regulation studied in vitro. Hyperregulation of the hemolymph osmotic pressure and cell volume regulation both occurred in salines at approximately 800 mosM and below. During long-term equilibration of the crabs to a wide range of saline environments, the total concentration of hemolymph amino acids plus taurine remained below 3 mM. During the first 6 h after an acute osmotic stress to the whole animal, the hemolymph osmotic pressure and Na activity gradually decreased, whereas the free amino acids remained below 3 mM. As the hemolymph osmotic pressure decreased below approximately 850 mosM, the amino acid level began to increase to 17-25 mM. This change was primarily due to increases in glycine, proline, taurine, and alanine. The likely source of the increase in hemolymph free amino acids in vivo is the free amino acid loss from muscle cells observed during cell volume regulation in vitro.

scholarly journals Quantification of Phytochemicals from CommercialSpirulinaProducts and Their Antioxidant Activities

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Naif Abdullah Al-Dhabi ◽  
Mariadhas Valan Arasu
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
High Performance ◽  
Antioxidant Activities ◽  
Analytical Techniques ◽  
Essential Amino Acids

The present study aimed to profile the polyunsaturated fatty acids, sugars, free amino acids, and polyphenols in 37 varieties ofSpirulinacommonly available in the market using gas chromatography and high performance liquid chromatography. In addition, the biological potentials of theSpirulinasamples were evaluated by analysing thein vitroantioxidant activities using various analytical techniques. The analyses revealed the presence of 13 polyunsaturated fatty acids, 18 amino acids, 7 sugars, and polyphenols. The polyunsaturated fatty acids contents were varied betweenSpirulinasamples. The total polyunsaturated fatty acids amount was 4.25 mg/100 g, and the average among of sapienic acid detected was 2.25 mg/100 g, which was followed by linoleic acid (16.7%) andγ-linolenic acid (14%). Among the 7 sugars, the hexose levels were the highest (73.85%). The total amino acids contents ranged from 11.49 to 56.14 mg/100 g, and the individual essential amino acids accounted for 17% to 39.18%. The “natural” tablets exhibited the highest polyphenols levels (24 mg/g). All of theSpirulinasamples expressed dose-dependent antioxidant activities. The polyunsaturated fatty acids, sugars, free amino acids, and polyphenols contents varied widely, and the variations in these compounds between theSpirulinasamples were significant.

scholarly journals Free amino acids exhibit anthozoan "host factor" activity: they induce the release of photosynthate from symbiotic dinoflagellates in vitro.

1995 ◽  
Vol 92 (16) ◽  
pp. 7430-7434 ◽  
Author(s):  
R. D. Gates ◽  
O. Hoegh-Guldberg ◽  
M. J. McFall-Ngai ◽  
K. Y. Bil ◽  
L. Muscatine
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Host Factor ◽  
Factor Activity ◽  
Symbiotic Dinoflagellates
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