scholarly journals Studies on a wide-spectrum intestinal dipeptide uptake system in the monkey and in the human

1975 ◽  
Vol 146 (1) ◽  
pp. 133-139 ◽  
Author(s):  
M Das ◽  
A N Radhakrishnan
Keyword(s):  
Amino Acids ◽  
Wide Spectrum ◽  
Intestinal Transport ◽  
Uptake System ◽  
Efflux Rate ◽  
Leucine Uptake ◽  
Dipeptide Uptake ◽  
In Vitro Uptake ◽  
Broad Specificity

1. The intestinal transport of glycine and leucine residues of glycyl-L-leucine was studied in the monkey and in the human in vitro. Uptake of both [14C]glycyl-L-leuine and glycyl-L-[14C]leucine show similar Kt values, but there is a marked difference in the Vmax. values. Preliminary studies suggest that this anomalous difference in the Vmax. values may be due to the greater efflux rate of glycine from the tissue. 2. Arrhenius plots of both [14C]glycyl-L-leucine uptake and glycyl-L-[14C]leucine uptake in the monkey intestine show a discontinuity at about 20 degrees C. The activation energies above and below the discontinuity are similar for both [14C]glycyl-L-leucine uptake and glycyl-L-[14C]leucine uptake. These similarities in uptake characteristics suggest that the dipeptide glycyl-L-leucine is transported as one unit. 3. In the monkey intestine, glycyl-L-leucine uptake is inhibited by a wide variety of dipeptides, including those containing acidic and basic amino acids. The inhibition was shown to be competitive by using four representative dipeptides namely: L-alanyl-L-alanine, L-alanyl-L-leucine, L-glutamyl-L-glutamic acid and L-lysyl-L-lysine. The results strongly suggest that in the monkey intestine there may be a dipeptide-uptake system with an extremely broad specificity. These results were also confirmed in the human in a limited way.

Uptake of l-Leucyl-l-Leucine and Glycylsarcosine by Hamster Jejunum in Vitro

1983 ◽  
Vol 65 (2) ◽  
pp. 177-184 ◽  
Author(s):  
D. M. Matthews ◽  
D. Burston
Keyword(s):  
Amino Acid ◽  
Intestinal Transport ◽  
Inhibitory Effect ◽  
Complete Inhibition ◽  
Maximal Velocity ◽  
Uptake System ◽  
Apparent Affinity ◽  
Kinetics Of Uptake ◽  
Dipeptide Uptake

1. Preliminary observations of the effects on intestinal transport of the lipophilic properties of the amino acid side chains of a series of neutral dipeptides showed that, contrary to expectation, l-valyl-l-valine and not l-leucyl-l-leucine was the most powerful inhibitor of uptake of the hydrolysis-resistant dipeptide glycylsarcosine by hamster jejunum in vitro. 2. Investigation of the kinetic characteristics of uptake of l-leucyl-l-leucine showed that Kt and Vmax. were lower than the corresponding values for l-valyl-l-valine, suggesting a higher apparent affinity for transport and a lower maximal velocity of transport. Ki for the inhibitory effect of l-leucyl-l-leucine on uptake of glycylsarcosine was less than one-half of the Kt for l-leucyl-l-leucine, so that inhibition was stronger than that expected from the apparent affinity for transport obtained from the kinetics of uptake of the inhibitor. In spite of this, l-leucyl-l-leucine was a much less powerful inhibitor of uptake of glycylsarcosine than was l-valyl-l-valine. 3. The results suggest that total uptake of l-leucyl-l-leucine at pH 5 is the result of at least two processes: uptake of intact peptide by one or more mechanisms, and also hydrolysis followed by uptake of free amino acid. At most concentrations, more than half the mediated uptake of l-leucyl-l-leucine was in the form of intact peptide. 4. The results of experiments on competition for uptake between dipeptides were unexpected. l-leucyl-l-leucine could inhibit mediated uptake of intact glycylsarcosine completely, but glycylsarcosine could not cause complete inhibition of mediated uptake of intact l-leucyl-l-leucine. Glycylsarcosine could, however, cause complete inhibition of mediated uptake of intact l-valyl-l-valine, which in turn could cause complete inhibition of mediated uptake of intact l-leucyl-l-leucine. The existence of more than one dipeptide uptake system in the small intestine seems probable.

Intestinal transport of amino acids studied in vitro with l-[131I]monoiodotyrosine

1960 ◽  
Vol 41 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Daniel Nathans ◽  
Donald F. Tapley ◽  
Joan E. Ross
Keyword(s):  
Amino Acids ◽  
Intestinal Transport

Amino group requirement for in vitro intestinal transport of amino acids

1962 ◽  
Vol 202 (1) ◽  
pp. 171-173 ◽  
Author(s):  
Richard P. Spencer ◽  
Ted M. Bow ◽  
Mary Anne Markulis
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Cinnamic Acid ◽  
Concentration Gradient ◽  
Anthranilic Acid ◽  
Intestinal Transport ◽  
Amino Group ◽  
Phenylpyruvic Acid ◽  
Phenyllactic Acid

The amino group requirement for transintestinal transport of amino acids against a concentration gradient was investigated using hamster everted intestinal sacs. Although glycine (5 x 10–3 m) was transported against a concentration gradient, acetic acid was not. Similarly, l-phenylalanine was transported, whereas phenylpyruvic acid, phenylpropionic acid, phenyllactic acid, and cinnamic acid were not. l-Tryptophan was transported, but indolyllactic acid was not. The amino group was thus essential for transport by this system. n-Methylglycine and l-proline were accumulated from mucosa to serosa against a concentration gradient. Hence, one hydrogen of the amino group can be replaced. However, n-phenylglycine was not accumulated across these preparations, suggesting that the moiety replacing the amino hydrogen can not be sterically bulky. α-l-Alanine was transported against a concentration gradient from mucosa to serosa, but ß-alanine was not. This is in contrast to other systems which accumulate ß-alanine against a concentration gradient. Anthranilic acid, with the amino group in a relative ß position, was also not accumulated across everted intestinal sacs.

In Vitro Uptake of Labelled Amino Acids by the Skin of Children with Generalized Congenital Analgesia

1969 ◽  
Vol 08 (01) ◽  
pp. 83-88
Author(s):  
J. Merzel ◽  
G. Blumen ◽  
B. J. Schmidt ◽  
J. C. Maia ◽  
I. Raw ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Aromatic Amino Acids ◽  
Relationship Of ◽  
In Vitro Uptake

SummaryThe “in vitro” uptake of labelled tyrosine, tryptophan and leucine by the skin of two children with GCA (Generalized Congenital Analgesia) was compared with that in normal (white and negro) individuals. Through radioactivity counts and radioautographic procedures it was shown that the uptake of the two aromatic amino acids was reduced in the GCA individuals the protein synthesis seemed to be normal.The possible relationship of these results to an abnormal metabolite isolated from the urine of these patients is discussed.

Uptake of a Series of Neutral Dipeptides Including l-Alanyl-l-Alanine, Glycylglycine and Glycylsarcosine by Hamster Jejunum in Vitro

1984 ◽  
Vol 67 (5) ◽  
pp. 541-549 ◽  
Author(s):  
D. M. Matthews ◽  
D. Burston
Keyword(s):  
Amino Acids ◽  
Free Amino ◽  
Inhibitory Effect ◽  
Progressive Increase ◽  
The Other ◽  
Uptake System ◽  
Apparent Affinity ◽  
Inhibitory Ability ◽  
Kinetics Of

1. This paper is the last of a set reporting an investigation of the kinetics of jejunal uptake and inhibitory ability of a series of neutral dipeptides, glycylglycine, l-ananyl-l-alanine, l-valyl-l-valine and l-leucyl-l-leucine, with progressively longer and more lipophilic side chains. 2. The results suggested that at pH 5, uptake of l-alanyl-l-alanine, like that of l-valyl-l-valine and l-leucyl-l-leucine, was the result of two processes, uptake of intact peptide and uptake of free amino acid released extracellularly. On the other hand, uptake of glycylglycine was entirely in the form of intact peptide. In contrast to uptake of l-valyl-l-valine and l-leucyl-l-leucine, the proportion of intact l-alanyl-l-alanine taken up by mediated transport was greatest at the lowest concentration studied and smallest at the highest concentration. 3. Taking the series of results as a whole, whereas the corresponding series of amino acids, glycine, l-alanine, l-valine and l-leucine, showed a progressive increase in apparent affinity for uptake and a decrease in Vmax., we could find no such regular progression with the peptides. 4. The results of work on inhibition of uptake of one dipeptide by another were unexpectedly complex. Examples were the very powerful inhibitory effect of l-valyl-l-valine on uptake of glycylsarcosine, not suggested by the Kt of the former peptide, and the failure of glycylsarcosine to cause complete inhibition of uptake of l-alanyl-l-alanine and l-leucyl-l-leucine, though it could completely inhibit uptake of l-valyl-l-valine. There may be more than one uptake system for intact peptides, but we cannot yet suggest an explanation for all the results on inhibitions of uptake.

Sign in / Sign up

Export Citation Format

Share Document