Specificity of L-Alanine Transport in the Spine Epithelium of Paracentrotus Lividus (Echinoidea)

1978 ◽  
Vol 58 (2) ◽  
pp. 425-440 ◽  
Author(s):  
M. E. de Burgh
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Active Transport ◽  
Marine Invertebrates ◽  
Paracentrotus Lividus ◽  
Arenicola Marina ◽  
Nereis Virens ◽  
Alanine Transport ◽  
Active Transport System ◽  
Digestive Glands

In many marine invertebrates the presence of an active transport system for the epithelial absorption of amino acids has been conclusively demonstrated (Stephens, 1968. 1972; West, de Burgh & Jeal, 1977). It has been observed by several authors that inhibition of uptake of a given amino acid can occur in the presence of other amino acids, in a manner analogous to that observed in vertebrate gut absorption systems. Some examples are the work of Chapman & Taylor (1969) on whole Nereis virens, Ferguson (1968) on the digestive glands of Echinaster spinulosus, Ferguson (1971) on whole asteroids, Bamford & Stewart (1973 a, b) on Arenicola marina gut, and Bamford & McCrea (1975) on the gill of Cerastoderma edule.

Some Observations On Platelet Amino Acid Transport Systems

1981 ◽  
Author(s):  
U T Yardimci ◽  
A Özbilen ◽  
O N Ulutin
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Active Transport ◽  
Amino Acid Transport ◽  
Acid Group ◽  
Transport Systems ◽  
Acid Transport ◽  
Amino Acid Group ◽  
Active Transport System ◽  
Group Transport

We have studied the transport systems for amino acids in platelets. Na+/K+ dependent active transport systems were found to be responsible for the transport of amino acids through the platelet membrane (Km’s being at uM ranges). We have also isolated the binding proteins for amino acids from platelet membranes as the carriers involved in these active transport systems by cold osmotic shock procedure. Each amino acid besides being transported by a specific active transport system may be subject to transport by group amino acid transport systems.Group amino acid transport systems are classified by countertransport experiments as follows: Neutral amino acid group transport systems: IA: glycine, alanine, serine, threonine IB: valine, leucine, isoleucine, serine,threonine IC: cysteine, methionine, proline Basic amino acid group transport systems: lie: lysine IIB: histidine, arginine Acidic amino acid group transport systems: III A: Aspartic acid, glutamic acid Aromatic amino acid group transport systems: IVC: Phenylalanine,tyrosine, histidine, proline.

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.

Absorption of L-alanine and other dissolved nutrients by the spines of Paracentrotus lividus (Echinoidea)

1977 ◽  
Vol 57 (4) ◽  
pp. 1031-1045 ◽  
Author(s):  
M. E. de Burgh ◽  
A. B. West ◽  
F. Jeal
Keyword(s):  
Amino Acids ◽  
Organic Molecules ◽  
Marine Invertebrates ◽  
Analytical Techniques ◽  
Paracentrotus Lividus ◽  
Direct Absorption ◽  
Dissolved Nutrients ◽  
Recent Developments ◽  
Modern Analytical

The possibility that marine invertebrates might obtain part of their nutritional requirements by direct absorption of dissolved molecules through the epidermis has recently received considerable attention. This revival of interest in a field which had been virtually abandoned since the early part of the century was led by the findings of Stephens & Schinske (1957, 1958, 1961). Modern analytical techniques have revealed that the amount of dissolved nutrients in coastal waters is much greater than was formerly realized; total amino acids have been recorded in concentrations of up to 10-4 mole/litre in south-east Alaskan waters (Schell, 1974) and 7 x 10-5 mole/litre off Helgoland (Bohling, 1970). Direct absorption of amino acids has been conclusively established in several phyla (see reviews by Stephens, 1968,1972), and one of the major aims of current research is to show that dissolved organic molecules taken up from available concentrations could be of nutritional significance. Recent developments concerning the possible roles of uptake in marine ecosystems have been reviewed by West, de Burgh & Jeal (1977).

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.

Characterisation of Amino Acid Transport in Red Blood Cells of a Primitive vertebrate, the Pacific Hagfish (Eptatretus Stouti)

1990 ◽  
Vol 154 (1) ◽  
pp. 355-370 ◽  
Author(s):  
DARON A. FINCHAM ◽  
MICHAEL W. WOLOWYK ◽  
JAMES D. YOUNG
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Red Blood Cells ◽  
Amino Acid Transport ◽  
Blood Cells ◽  
Red Cells ◽  
Acid Transport ◽  
Intracellular Amino Acid ◽  
Alanine Transport ◽  
The Pacific

Intracellular amino acid levels and the characteristics of amino acid transport were investigated in red blood cells of a primitive vertebrate, the Pacific hagfish (Eptatretus stouti Lockington). In contrast to red cells from euryhaline teleosts and elasmobranchs, which contain high concentrations of β-amino acids, those from hagfish exhibited an intracellular amino acid pool (approx. lOOmmoll−1cell water) composed almost entirely of conventional aαamino acids. Red cell:plasma distribution ratios for individual amino acids ranged from 219, 203 and 173 for alanine, αaminonbutyrate and proline, respectively, to 11 and 13 for lysine and arginine. Corresponding distribution ratios for Na+, K+ and Cl− were 0.043, 21 and 0.32, respectively. The cellular uptake of amino acids, with the exception of Lproline and glycine, was Na+-independent. Compared with mammalian and avian red cells, those from hagfish exhibited 104-fold higher rates of L-alanine transport. Uptake of this amino acid from the extracellular medium was concentrative, but occurred as a 1:1 exchange with intracellular amino acids. The L-alanine transport mechanism was identified as an asc-type system on the basis of its Na+ independence and selectivity for neutral amino acids of intermediate size. A volume-sensitive amino acid channel, which is found in both euryhaline teleosts and in elasmobranchs, is absent from hagfish red cells.

Evidence for Active Transport of the Dipeptide Carnosine (β-Alanyl-l-Histidine) by Hamster Jejunum in Vitro

1974 ◽  
Vol 46 (6) ◽  
pp. 693-705 ◽  
Author(s):  
D. M. Matthews ◽  
Jill M. Addison ◽  
D. Burston
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Active Transport ◽  
Amino Acid Mixture ◽  
Intestinal Wall ◽  
Free Form ◽  
Acid Mixture ◽  
Total Uptake ◽  
Hydrolysis Of

1. The characteristics of intestinal transport and hydrolysis of carnosine (β-alanyl-l-histidine) have been studied in rings of everted hamster jejunum in vitro. 2. During incubation with carnosine, large amounts of intact peptide appeared in the intestinal wall, accompanied by small amounts of the constituent amino acids in the free form. Although there was some extracellular hydrolysis, the free amino acids appearing in the intestinal wall were almost entirely derived from intracellular hydrolysis of the peptide. Incubation in l-alanyl-l-histidine resulted in uptake of the constituent amino acids in the free form without appearance of intact peptide in the intestinal wall. 3. Total uptake of β-alanine (both peptide-bound and free) and total uptake of histidine were greater from a low concentration (1 μmol/ml) of carnosine than uptake of these amino acids from the equivalent amino acid mixture. At a high concentration of carnosine (20 μmol/ml), total uptake of β-alanine was greater from the peptide than from the equivalent amino acid mixture but total uptake of histidine was less. At this concentration, total uptake of β-alanine plus total uptake of histidine from the peptide was approximately the same as from the amino acid mixture. 4. Uptake of carnosine by jejunal rings was the result of a saturable process (Kt 9·4 μmol/ml, Vmax. 2·7 μmol g−1 initial wet wt. min−1). Intact carnosine was concentrated in the intestinal wall, the concentration ratio between intracellular fluid and incubation medium being up to 3·4/1. Uptake of carnosine was reduced by anoxia, metabolic inhibitors and replacement of medium Na+. Na+-dependent active transport was shown to be involved in uptake of carnosine by hamster jejunum in vitro.

Characterization of a broad-scope amino acid transport system in sand dollars

1988 ◽  
Vol 254 (3) ◽  
pp. R485-R490 ◽  
Author(s):  
J. P. Davis ◽  
S. Bellis ◽  
G. C. Stephens
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Transport System ◽  
Isobutyric Acid ◽  
Amino Acid Transport System ◽  
Neutral Amino Acids ◽  
Broad Scope ◽  
Alanine Transport ◽  
Sand Dollars

Both echinoderm embryos and adults take up alpha-amino acids by an apparent broad-scope transport system. This transporter can be characterized as follows: alanine transport is not blocked by alpha-(methylamino)isobutyric acid. Leucine and other lipophilic neutral amino acids are preferentially transported. Transport is sodium dependent and blocked by 2-aminobicyclo-[2,2,1]heptane-2-carboxycylic acid. Lysine and aspartate transport is inhibited by lipophilic neutral amino acids. Taurine, a beta-neutral amino acid, is translocated via a second and independent carrier.

AMINO ACID ACCUMULATION IN EHRLICH ASCITES CARCINOMA CELLS

1960 ◽  
Vol 38 (1) ◽  
pp. 1311-1326 ◽  
Author(s):  
A. Tenenhouse ◽  
J. H. Quastel
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Amino Acid ◽  
Active Transport ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Ion Concentration ◽  
Metabolic Inhibitors ◽  
Ehrlich Ascites ◽  
Glycine Transport

Measurements of the transport of amino acids into Ehrlich ascites carcinoma cells have shown that the following relationship exists between the intracellular steady-state concentration of the amino acid (Cx) and the extracellular concentration (C0):[Formula: see text]where Cm is the maximum intracellular concentration (formed when C0 is large) and Em is a constant. It is shown that Em is identical with Km, the Michaelis constant, if a carrier enzyme is involved in the process of active transport and is, therefore, a measure of the affinity of the amino acid for the effective agent involved in the transport phenomenon.The ratio of the steady-state intracellular and extracellular concentrations of amino acids exceeds unity with all amino acids examined. The responses of L-S-ethylcysteine transport to changes of potassium ion concentration and to changes of temperature differ from those of glycine transport and indicate that different carriers are involved in the active transport of these amino acids into Ehrlich ascites cells. This conclusion is supported by the fact that, whereas glycine and L-serine compete with each other for concentrative uptake, such mutual competition does not occur between S-ethylcysteine and glycine or L-serine or L-leucine.Effects of the metabolic inhibitors, 2,4-dinitrophenol, iodoacetate, and stilbestrol show that these substances exercise inhibitory effects on active transport of amino acids by suppression of respiratory or glycolytic energy. Stilbestrol, which is a particularly potent inhibitor, is more effective under aerobic conditions (in the absence of glucose) than under anaerobic conditions (in the presence of glucose). It is reasonable to account for these results on the hypothesis that the carrier responsible for amino acid transport is ATP dependent and that the carrier breaks down, and is no longer available for amino acid transfer, if the ATP content of the cell is depleted.

Construction of Bacterial Cells with an Active Transport System for Unnatural Amino Acids

2019 ◽  
Vol 8 (5) ◽  
pp. 1195-1203 ◽  
Author(s):  
Wooseok Ko ◽  
Rahul Kumar ◽  
Sanggil Kim ◽  
Hyun Soo Lee
Keyword(s):  
Amino Acids ◽  
Active Transport ◽  
Transport System ◽  
Unnatural Amino Acids ◽  
Bacterial Cells ◽  
Active Transport System
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