Specificity of the transport system for neutral amino acids in the hamster intestine

1962 ◽  
Vol 202 (5) ◽  
pp. 919-925 ◽  
Author(s):  
Edmund C. C. Lin ◽  
Hiroshi Hagihira ◽  
T. Hastings Wilson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Transport System ◽  
Side Chain ◽  
Carboxyl Group ◽  
Amino Group ◽  
Methyl Group ◽  
Neutral Amino Acids ◽  
Active Transport System ◽  
Everted Sacs

The specificity of the active transport system for neutral amino acids has been studied with everted sacs of hamster intestine. Amino acids with modifications or replacements of the carboxyl, amino, or α-hydrogen groups were poorly transported and were poor inhibitors of the transport of other l-amino acids. The carboxyl group must remain free, the amino group must not be in the tertiary or quaternary state, and the α-hydrogen can not be replaced by a methyl group without serious effect on the transport rate. It was concluded that the l-amino acids were distinguished from the d-isomers by the interaction of the carrier with the carboxyl group, the amino group, and the α-hydrogen. The side chain of the amino acid must be nonpolar but there is relatively little restriction on its structure.

Uptake of L-proline by Histoplasma capsulatum

1976 ◽  
Vol 22 (8) ◽  
pp. 1188-1190 ◽  
Author(s):  
Nina Dabrowa ◽  
Dexter H. Howard
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Active Transport ◽  
Transport System ◽  
Histoplasma Capsulatum ◽  
Yeast Cells ◽  
Side Chain ◽  
Simple Diffusion ◽  
Aliphatic Side Chain ◽  
Active Transport System

The uptake and incorporation of L-proline by yeast cells of the dimorphic zoopathogen Histoplasma capsulatum were studied. The amino acid was assimilated in at least two ways: by an active transport system with a Km of 1.7 × 10−5 M and by simple diffusion. The active transport system was stereospecific and severely restricted to neutral aliphatic side-chain amino acids. Certain analogues inhibited L-proline uptake and prevented incorporation of the amino acid into cellular constituents. The inhibition of L-proline uptake by L-leucine was competitive. Since L-leucine and L-proline are seemingly transported by a system with similarcharacteristics, it must be concluded, as originally postulated, that the buckled ring of L-proline, in solution, acts as an aliphatic side chain and that this cyclic amino acid is transported by a system more or less specific for amino acids with neutral aliphatic side chains.

Interactions of neutral and acidic amino acids in renal tubular transport

1962 ◽  
Vol 202 (3) ◽  
pp. 577-583 ◽  
Author(s):  
William A. Webber
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Side Chain ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular Transport ◽  
Renal Tubular ◽  
Amino Acid Concentrations

The effects of intravenous infusions of a variety of neutral and acidic amino acids on the plasma concentrations and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations were determined by ion exchange column chromatography. Infusion of either l-glutamic acid or l-aspartic acid caused a gross increase in the plasma concentration and excretion of the other. Infusions of neutral amino acids including glycine, l-alanine, l-leucine, l-methionine, l-proline, and l-phenylalanine caused some minor changes in the endogenous plasma amino acid concentrations. They produced increases in the excretion of other neutral amino acids and, in some cases, of acidic and basic amino acids as well. In general, amino acids with long side chains were most effective in inhibiting reabsorption while cyclic side-chain compounds were less effective. There appear to be at least three somewhat separable mechanisms for renal tubular reabsorption of amino acids in dogs.

Intestinal Transport of Two Dipeptides Containing the Same Two Neutral Amino Acids in Man

1973 ◽  
Vol 45 (3) ◽  
pp. 291-299 ◽  
Author(s):  
D. B. A. Silk ◽  
D. Perrett ◽  
M. L. Clark
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Transport System ◽  
Amino Acid Transport ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Acid Transport ◽  
Peptide Hydrolysis ◽  
Amino Acid Transport System ◽  
Neutral Amino Acids

1. A double lumen perfusion technique has been used in man to study the absorption of the two neutral amino acids glycine and l-alanine from the two dipeptides, l-alanylglycine and glycyl-l-alanine and from an equivalent amino acid mixture. 2. Glycine was absorbed faster from the dipeptides than from the equivalent amino acid mixture, and the difference in absorption rates of glycine and alanine seen when the equimolar mixture of the amino acids was perfused, was abolished when either dipeptide was perfused. This suggests that dipeptides are taken up by the mucosal cell by a mechanism independent of the amino acid-transport system. 3. The presence of free amino acids in the lumen during perfusion of both dipeptides suggests that hydrolysis occurs at some stage in the uptake process. Intraluminal hydrolysis was insufficient to account for the concentration of the amino acids seen, and their presence is thought to be due to hydrolysis of the dipeptides at the brush border. 4. It is suggested that these results confirm that at least two modes of peptide absorption occur simultaneously, namely, direct peptide uptake, and peptide hydrolysis with subsequent absorption of the released amino acids by the amino acid transport system.

Transformation of the Carboxyl Group of an Amino Acid to Variously Substituted Imidazoles through a Davidson-Type Heterocyclization

Synthesis ◽  
2019 ◽  
Vol 51 (09) ◽  
pp. 1961-1968 ◽  
Author(s):  
Jim Küppers ◽  
Michaela Hympánová ◽  
Tim Keuler ◽  
Andreas Schneider ◽  
Gregor Schnakenburg ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Amino Acids ◽  
Amino Acid ◽  
Carboxylic Acid ◽  
Building Blocks ◽  
Carboxyl Group ◽  
Amino Group ◽  
Combinatorial Approach ◽  
X Ray ◽  
Imidazole Derivatives

The modification of amino acids leads to valuable building blocks for the synthesis of bioactive compounds. By keeping the amino group protected, the carboxylic acid functionality can be converted in two steps into an imidazole moiety via a Davidson-like heterocyclization. This reaction allows for a combinatorial approach, in which two positions at the heterocycle can be modified. Herein, we report the synthesis of such imidazole derivatives by employing N-protected cyclohexylalanine as the starting material. Different α-halo ketones were used and two points of diversity, positions 4 and 5, were examined. The structure of the final imidazole derivatives was confirmed by three X-ray crystal structure analyses and their protease inhibiting activities were evaluated.

CHARACTERISTICS OF ACIDIC AMINO ACID TRANSPORT IN MAMMALIAN KIDNEY

1963 ◽  
Vol 41 (1) ◽  
pp. 131-137 ◽  
Author(s):  
William A. Webber
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Tubular Reabsorption ◽  
Side Chain ◽  
Acid Transport ◽  
Acidic Amino Acid ◽  
Neutral Amino Acids ◽  
Wide Range ◽  
Renal Tubular

A series of clearance experiments on dogs were carried out which were designed to confirm and characterize the renal tubular reabsorption of glutamic and aspartic acids. Tubular reabsorption was measured and found to reach a maximum of about 100 μmole/minute for L-glutamic and L-aspartic acids and a slightly lower level for D-aspartic. Competitive studies using substituted amino acids were performed and three patterns of inhibition of amino acid reabsorption observed. Acidic amino acids inhibited the reabsorption of each other, while neutral amino acids (and an acidic amino acid substituted so as to have a neutral side chain) inhibited the reabsorption of a wide range of other amino acids. Compounds with the amino group or either carboxyl group substituted or absent, but not resembling neutral amino acids, were not inhibitory. There appears to be a specialized mechanism for acidic amino acid transport which probably requires all three functional groups but which may be interfered with by a compound with alpha carboxyl and amino groups and a neutral side chain.

scholarly journals Transport system ASC for neutral amino acids. An electroneutral sodium/amino acid cotransport sensitive to the membrane potential.

1992 ◽  
Vol 267 (12) ◽  
pp. 8330-8335
Author(s):  
O Bussolati ◽  
P.C. Laris ◽  
B.M. Rotoli ◽  
V Dall'Asta ◽  
G.C. Gazzola
Keyword(s):  
Amino Acids ◽  
Membrane Potential ◽  
Amino Acid ◽  
Transport System ◽  
Neutral Amino Acids

scholarly journals The zebrafish cationic amino acid transporter/glycoprotein-associated family: sequence and spatiotemporal distribution during development of the transport system b0,+ (slc3a1/slc7a9)

2021 ◽  
Author(s):  
Ståle Ellingsen ◽  
Shailesh Narawane ◽  
Anders Fjose ◽  
Tiziano Verri ◽  
Ivar Rønnestad
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Transport System ◽  
Expression Patterns ◽  
Amino Acid Transporter ◽  
Rapid Screening ◽  
Cationic Amino Acid ◽  
Large Neutral Amino Acids ◽  
Neutral Amino Acids ◽  
Acid Transporter

AbstractSystem b0,+ absorbs lysine, arginine, ornithine, and cystine, as well as some (large) neutral amino acids in the mammalian kidney and intestine. It is a heteromeric amino acid transporter made of the heavy subunit SLC3A1/rBAT and the light subunit SLC7A9/b0,+AT. Mutations in these two genes can cause cystinuria in mammals. To extend information on this transport system to teleost fish, we focused on the slc3a1 and slc7a9 genes by performing comparative and phylogenetic sequence analysis, investigating gene conservation during evolution (synteny), and defining early expression patterns during zebrafish (Danio rerio) development. Notably, we found that slc3a1 and slc7a9 are non-duplicated in the zebrafish genome. Whole-mount in situ hybridization detected co-localized expression of slc3a1 and slc7a9 in pronephric ducts at 24 h post-fertilization and in the proximal convoluted tubule at 3 days post-fertilization (dpf). Notably, both the genes showed co-localized expression in epithelial cells in the gut primordium at 3 dpf and in the intestine at 5 dpf (onset of exogenous feeding). Taken together, these results highlight the value of slc3a1 and slc7a9 as markers of zebrafish kidney and intestine development and show promise for establishing new zebrafish tools that can aid in the rapid screening(s) of substrates. Importantly, such studies will help clarify the complex interplay between the absorption of dibasic amino acids, cystine, and (large) neutral amino acids and the effect(s) of such nutrients on organismal growth.

CHARACTERISTICS OF ACIDIC AMINO ACID TRANSPORT IN MAMMALIAN KIDNEY

1963 ◽  
Vol 41 (1) ◽  
pp. 131-137 ◽  
Author(s):  
William A. Webber
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Tubular Reabsorption ◽  
Side Chain ◽  
Acid Transport ◽  
Acidic Amino Acid ◽  
Neutral Amino Acids ◽  
Wide Range ◽  
Renal Tubular

A series of clearance experiments on dogs were carried out which were designed to confirm and characterize the renal tubular reabsorption of glutamic and aspartic acids. Tubular reabsorption was measured and found to reach a maximum of about 100 μmole/minute for L-glutamic and L-aspartic acids and a slightly lower level for D-aspartic. Competitive studies using substituted amino acids were performed and three patterns of inhibition of amino acid reabsorption observed. Acidic amino acids inhibited the reabsorption of each other, while neutral amino acids (and an acidic amino acid substituted so as to have a neutral side chain) inhibited the reabsorption of a wide range of other amino acids. Compounds with the amino group or either carboxyl group substituted or absent, but not resembling neutral amino acids, were not inhibitory. There appears to be a specialized mechanism for acidic amino acid transport which probably requires all three functional groups but which may be interfered with by a compound with alpha carboxyl and amino groups and a neutral side chain.

Succinimidyl esters of fatty acids for amino acid acylations

1976 ◽  
Vol 54 (5) ◽  
pp. 733-737 ◽  
Author(s):  
Alenka Paquet
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Amino Acid ◽  
Free Amino ◽  
Side Chain ◽  
Amino Acid Esters ◽  
Amino Group ◽  
Acyl Chlorides ◽  
Hydroxysuccinimide Esters ◽  
Acid Esters

Fatty acid N-hydroxysuccinimide esters have been prepared from the thallium(I) salt of N-hydroxysuccinimide and the corresponding acyl chlorides in essentially quantitative yields. These active esters were used for acylation of amino acid esters in organic solvents, or of free amino acids in aqueous medium. The title compounds were found to be selective towards the side chain amino group of lysine. An efficient preparation of ε-N-benzyloxycarbonyl-L-lysine using benzyl succinimidyl carbonate is described.

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