Binding and Uptake of Amino Acids by Brain Tissue

1973 ◽  
Vol 51 (2) ◽  
pp. 121-128 ◽  
Author(s):  
P. C. Shiu ◽  
K. A. C. Elliott
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sodium Chloride ◽  
Incubation Medium ◽  
Sucrose Solution ◽  
The Other ◽  
Percentage Increase ◽  
Endogenous Amino Acids ◽  
Sodium Dependent ◽  
Net Uptake

(1) Of the endogenous glutamate, aspartate, alanine, glycine, and γ-aminobutyrate (GABA), 26–37% remains bound in particles when rat brain is homogenized in isosmotic salt-free sucrose solution; a smaller proportion, 16%, of the glutamine is bound. The amounts bound are increased if sodium chloride is present; the percentage increase is greatest in the case of GABA, followed by glutamate, and least with glutamine. When tracer amounts of radioactive amino acids are present in the solution in the absence of salt very little radioactivity appears in bound GABA or glutamine, but appreciable amounts are found in the other amino acids. In the presence of sodium chloride, the total amount of bound amino acid increases as does, to a lesser extent, the radioactivity bound. Ouabain and protoveratrine seem to cause some release of sodium-dependent binding of the amino acids; this is most marked with GABA.(2) Slices incubated in the presence of oxygen and glucose take up each of the amino acids when these are added to the incubation medium. The highest intracellular concentration and the greatest net uptake occur with GABA. The endogenous concentration of glutamate is higher than that of the other amino acids but the net uptake is the least. The highest ratios of uptake to endogenous content occur with alanine and glycine. Determinations of radioactivity indicate that, in the cases of GABA and glycine, the increase in radioactivity in the slices is almost completely accounted for by uptake from the medium with almost no exchange. Some exchange occurs with other amino acids. Protoveratrine inhibits uptake of all the amino acids and actually causes loss of glutamate and aspartate from slices. Ouabain inhibits in all cases; the uptakes of glutamate and aspartate are least affected. Tetrodotoxin, alone or with either of the other two drugs, tends to increase uptake of all the amino acids. When the net uptake is inhibited by drugs considerable exchange of endogenous amino acids with radioactive amino acids in the medium is observed.

Ca2+-dependence of the evoked release from guinea pig cerebral cortex slices of endogenous 14C-labelled amino acids, labelled via D-[U-14C]glucose

1976 ◽  
Vol 54 (6) ◽  
pp. 953-956 ◽  
Author(s):  
S. J. Potashner
Keyword(s):  
Amino Acids ◽  
Cerebral Cortex ◽  
Amino Acid ◽  
Guinea Pig ◽  
The Other ◽  
Major Portion ◽  
Free Medium ◽  
Spontaneous Release ◽  
Endogenous Amino Acids ◽  
Cortex Slices

Spontaneous and electrically evoked release of exogenous labelled amino acids and endogenous amino acids labelled from D-[U-14C]glucose were compared in control and Ca2+-free medium using guinea pig cerebral cortex slices. Spontaneous release of all labelled amino acids, except that of endogenous 14C-labelled threonine–serine–glutamine (unseparated) and exogenous [14C]aspartate, was doubled in Ca2+-free medium. The major portion of the electrically evoked release of endogenous [14C]glutamate, [14C]aspartate, γ-amino[14C]butyrate (14C-labelled GABA) and exogenous 3H-labelled GABA was Ca2+-dependent. More than half of the evoked release of the other labelled amino acids was Ca2+-independent. As the pattern of Ca2+-dependence of the evoked releases concurred with the selectivity of the evoked release for endogenous [14C]-glutamate, [14C]aspartate, and 14C-labelled GABA, it was concluded that these labelled amino acids were probably released from the amino acid 'transmitter pool'.

Effect of Intraduodenal Starch Infusion on Net Portal Absorption of Amino Acids in Growing steers Fed Lucerne

1994 ◽  
Vol 1994 ◽  
pp. 28-28
Author(s):  
C.J. Seal ◽  
D.S. Parker ◽  
J.C. MacRae ◽  
G.E. Lobley
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Gastrointestinal Tract ◽  
Protein Turnover ◽  
Portal Blood ◽  
Intestinal Lumen ◽  
Short Term ◽  
Net Uptake ◽  
Amino Acid Requirements ◽  
Glucose Availability

Amino acid requirements for energy metabolism and protein turnover within the gastrointestinal tract are substantial and may be met from luminal and arterial pools of amino acids. Several studies have demonstrated that the quantity of amino acids appearing in the portal blood does not balance apparent disappearance from the intestinal lumen and that changing diet or the availability of energy-yielding substrates to the gut tissues may influence the uptake of amino acids into the portal blood (Seal & Reynolds, 1993). For example, increased net absorption of amino acids was observed in animals receiving exogenous intraruminal propionate (Seal & Parker, 1991) and this was accompanied by changes in glucose utilisation by the gut tissues. In contrast, there was no apparent change in net uptake of [l-13C]-leucine into the portal vein of sheep receiving short term intraduodenal infusions of glucose (Piccioli Cappelli et al, 1993). This experiment was designed to further investigate the effects on amino acid absorption of changing glucose availability to the gut with short term (seven hours) or prolonged (three days) exposure to starch infused directly into the duodenum.

scholarly journals Identification in skeletal muscle of a distinct extracellular pool of amino acids, and its role in protein synthesis

1971 ◽  
Vol 121 (5) ◽  
pp. 817-827 ◽  
Author(s):  
R. C. Hider ◽  
E. B. Fern ◽  
D. R. London
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Incubation Medium ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Longus Muscle ◽  
Kinetics Of

1. The kinetics of radioactive labelling of extra- and intra-cellular amino acid pools and protein of the extensor digitorum longus muscle were studied after incubations with radioactive amino acids in vitro. 2. The results indicated that an extracellular pool could be defined, the contents of which were different from those of the incubation medium. 3. It was concluded that amino acids from the extracellular pool, as defined in this study, were incorporated directly into protein.

scholarly journals Amino acid transport in normal and glutathione-deficient sheep erythrocytes

1976 ◽  
Vol 154 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J D Young ◽  
J C Ellory ◽  
E M Tucker
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Cell Types ◽  
The Other ◽  
Acid Transport ◽  
Sheep Erythrocytes ◽  
Uptake Rates

1. Uptake rates for 23 amino acids were measured for both normal (high-GSH) and GSH-deficient (low-GSH) erythrocytes from Finnish Landrace sheep. 2. Compared with high-GSH cells, low-GSH cells had a markedly diminished permeability to D-alanine, L-alanine, α-amino-n-butyrate, valine, cysteine, serine, threonine, asparagine, lysine and ornithine. Smaller differences were observed for glycine and proline, whereas uptake of the other amino acids was not significantly different in the two cell types.

Nutritional factors associated with seasonal population increase of cacao thrips, Selenothrips rubrocinctus (Giard) (Thysanoptera), on cashew, Anacardium occidentale

1963 ◽  
Vol 53 (4) ◽  
pp. 681-713 ◽  
Author(s):  
R. G. Fennah
Keyword(s):  
Amino Acids ◽  
Water Stress ◽  
Amino Acid ◽  
Acid Concentration ◽  
Leaf Tissue ◽  
The Other ◽  
Amino Acid Concentration ◽  
Population Increase ◽  
Bearing Surface ◽  
Wet Season

The feeding of the cacao thrips, Selenothrips rubrocinctus (Giard), on cashew, Anacardium occidentale, one of its host plants in Trinidad, West Indies, is considered in relation to the annual period of maximum population increase on this host and to the choice of feeding sites on individual leaves. On trees observed for three years, populations regularly increased during the dry season, from a low level in December and January to a peak in April or May, and then rapidly declined during the wet season. Even when thrips were most abundant, some trees were free from attack, and this could not be attributed to protective morphological features, to specific repellent substances in the leaf, or to chance. S. rubrocinctus was found to feed on leaves that were subjected to water-stress and to breed only on debilitated trees: the evidence suggested that the adequacy of its supply of nutrients depends on the induction of suitable metabolic conditions within the leaf by water-stress.Both nymphs and adults normally feed on the lower, stomata-bearing surface of the leaf, but in a very humid atmosphere only a weak preference is shown for this surface and if, under natural conditions, it is exposed to insolation by inversion of the leaf, the insects migrate to the other surface. Since the thrips were shown to be indifferent to bodily posture, the observation suggests that their behaviour is governed primarily by avoidance of exposure to undue heat or dryness and only secondarily by the attractiveness of the stomata-bearing surface.Leaves of cashew tend not to become infested while still immature, and become most heavily infested, if at all, soon after they have hardened. Breeding does not occur on senescent leaves. The positions of feeding thrips are almost random on leaves under abnormal water-stress, but otherwise conform to certain patterns that mainly develop in fixed sequence. On reversal of an undetached leaf and consequent transfer of thrips from one surface to the other, there is no appreciable change in their distribution pattern or the apparent acceptability of the substrate. Changes of pattern were readily induced by injury to the plant during a period of water-stress and less easily, or not at all, when water-stress was low. Injury of areas of the leaf by heat was followed by their colonisation by thrips, and partial severance of branches by increased attack on their leaves.Leaves detached from uninfested trees invariably became acceptable for feeding within four hours. During this period, leaf water-content declined and the ratios of soluble-carbohydrate content and α-amino acids to fresh-leaf weight fell slightly and rose considerably, respectively. In the field, the latter ratio was invariably higher for infested than for uninfested leaf tissue, even on portions of the same leaf. If the nutrient value of leaf tissue is determined by the rate at which α-amino acids are extractable through a stylet puncture, the observed change in acceptability for feeding following plucking may be accounted for by the increase in α-amino-acid concentration. Feeding that is restricted on any one tree to the margins of local leaf injuries during prolonged high water-stress and totally absent when stress is low can be correlated with an α-amino-acid content in the living marginal tissue that is high or low, respectively. The ability of thrips to establish themselves and breed on leaves of a particular tree in the dry season and their failure to do so on leaves of the same tree in the wet season conforms with the greater or less amino-acid concentration occurring in the leaf at these respective times.

scholarly journals Action of insulin and growth hormone on protein synthesis in muscle from non-hypophysectomized rabbits

1971 ◽  
Vol 125 (2) ◽  
pp. 515-520 ◽  
Author(s):  
P. J. Reeds ◽  
K. A. Munday ◽  
M. R. Turner
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Incubation Medium ◽  
Amino Acid Uptake ◽  
Diaphragm Muscle ◽  
Acid Uptake

The separate effects of insulin and growth hormone on the uptake and incorporation of five amino acids into diaphragm muscle from non-hypophysectomized rabbits has been examined. Both growth hormone and insulin, when present in the medium separately, stimulated the incorporation into protein of the amino acids, leucine, arginine, valine, lysine and histidine. Insulin also stimulated amino acid uptake, but growth hormone did not. When insulin and growth hormone were present in the incubation medium together, the uptake and incorporation of valine, the only amino acid studied under these conditions, tended to be greater than the sum of the separate effects of the two hormones.

Determination of total proteinogenic amino acids and taurine by pre-column derivatisation and UHPLC: Single Laboratory Validation, First Action 2019.09

2020 ◽  
Author(s):  
George Joseph ◽  
Asha Varughese ◽  
Ann Daniel
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Infant Formula ◽  
Retention Time ◽  
Sulfonic Acid ◽  
Internal Standard ◽  
The Other ◽  
Method Performance ◽  
Single Laboratory

Abstract Background A method has been developed and validated for selective, accurate and precise determination of total proteinogenic amino acids and taurine from Infant Formula and Adult/Pediatric Nutritional Formulas (powders, ready-to-feed liquids, and liquid concentrates). The method was reviewed by the AOAC INTERNATIONAL SPIFAN Expert Review Panel (ERP) during the 133rd AOAC Annual Meeting & Expo on September 7, 2019 in Denver, CO, USA and was recommended to First Action Official MethodsSM status. Objective The method involves protein hydrolysis to amino acids, a simple pre-column derivatisation of amino acids and separation of derivatised amino acids by UHPLC. The quantification of amino acids is performed by multi-point calibration using norvaline as the internal standard. The analytical method is capable of quantitative determination for 22 proteinogenic amino acids, but cannot be used to quantitate tryptophan, which is destroyed during the acid hydrolysis step. Asparagine is determined as aspartic acid and glutamine as glutamic acid. The cystine and cysteine are converted to S-2-carboxyethylthiocysteine (CYSx) and the derivative is separated from the other amino acids. Citrulline which is present in some matrices and it is separated from other amino acids is not included in the method performance evaluation in the single laboratory validation (SLV). Method The proposed method met all the performance requirement limits set in standard method performance requirements (SMPR) 2014.013 for total proteinogenic amino acids and taurine. The correlation coefficient of multi-point calibration was not less than 0.999 for any amino acids at any point in the SLV study confirming the validity of linear dynanic range (LDR) and linearity of the method. The individual amino acids in the chromatogram were identified by absolute retention time and relative retention time (RRT) with respect to the internal standard norvaline. There were no significant (S/N Ratio <10) interferences from the reagents or by-products of derivatisation and targeted matrices. The method demonstrated high selectivity. Result Accuracy of the method was validated using standard reference materials (NIST SRM 1869 and 1849a) and spike recovery studies. The amino acid results in the SRMs were within the ranges of Reference Mass Fraction Values. The accuracy of the method was corroboratively validated by spike recovery studies. The average spike recovery range between 93 to 107% ensure the accuracy of the method for amino acids and compliance to the AOAC SMPR 2014.013. Conclusions Precision data of the method demonstrate that it meets the stakeholder requirements as per the SMPR. The mean RSDr for all the amino acids for 17 matrices selected for the SLV were not more than 4%. The method is very sensitive and the LOQ can go down to approximately ten times lower than the SMPR requirements. The sensitivity of method is a direct reflection of its signal to noise ratio which ensures guaranteed method performance at the lower levels of amino acids in these matrices. Highlights Taurine (aminoethane sulfonic acid) unlike the other amino acids is a beta-sulfonic amino acid that is not used in protein synthesis but is found as a free amino acid in tissues. The acidic functional group (-COOH) in common amino acid is replaced with a sulfonic acid (-SO3H) group in Taurine. The method offers baseline separation of citrulline which is an alpha amino acid generally present in Infant Formula and Adult/Pediatric Nutritional products. The separation of citrulline eliminates the risk of interference of this compound with other amino acids. The method can also separate and quantitate hydroxyproline, an important component of collagen that is often used to quantitate collagen. The method is simple and does not include any proprietary chemicals or instruments and can be performed on any basic reverse phase UHPLC system with UV detection.

THE OXIDATION OF ESTRONE-16-C14BY PEROXIDASE

1962 ◽  
Vol 40 (1) ◽  
pp. 459-469 ◽  
Author(s):  
P. H. Jellinck ◽  
Louise Irwin
Keyword(s):  
Amino Acids ◽  
Hydrogen Peroxide ◽  
Amino Acid ◽  
Serum Albumin ◽  
Oxidase Activity ◽  
Water Soluble ◽  
The Other ◽  
Aerobic Incubation ◽  
Nitrogenous Compounds ◽  
Initial Generation

Aerobic incubation of estrone-16-C14with peroxidase in the presence of serum albumin and other proteins resulted in the formation of water-soluble, ether-insoluble metabolites in high percentage yields. Similar products were formed when protein was replaced by cysteine or tryptophan but none of the other amino acids tested had any effect. The evidence points to an initial generation of hydrogen peroxide from these nitrogenous compounds by the enzyme acting as an aerobic oxidase, and the subsequent peroxidation of estrone to highly reactive products. These then combine with the protein or amino acid or else undergo alternative reactions. A strong chemical bond is formed with albumin and attempts to release the estrone metabolites from it were unsuccessful. Uterine homogenates from estrogen-treated rats showing high DPNH oxidase activity contained no "peroxidase" as measured by the formation of water-soluble products from estrone in the presence of protein.

scholarly journals Adding Amino Acids to a Sucrose Diet Is Not Sufficient to Support Longevity of Adult Bumble Bees

Insects ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 247 ◽  
Author(s):  
Nils Grund-Mueller ◽  
Fabian A. Ruedenauer ◽  
Johannes Spaethe ◽  
Sara D. Leonhardt
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Bombus Terrestris ◽  
Sucrose Solution ◽  
Amino Acid Content ◽  
Well Being ◽  
Nutritional Composition ◽  
Nutrient Composition ◽  
Bumble Bees ◽  
Essential Amino Acid Content

Dietary macro-nutrients (i.e., carbohydrates, protein, and fat) are important for bee larval development and, thus, colony health and fitness. To which extent different diets (varying in macro-nutrient composition) affect adult bees and whether they can thrive on nectar as the sole amino acid source has, however, been little investigated. We investigated how diets varying in protein concentration and overall nutrient composition affected consumption, longevity, and breeding behavior of the buff-tailed bumble bee, Bombus terrestris (Hymenoptera: Apidae). Queenless micro-colonies were fed either natural nutrient sources (pollen), nearly pure protein (i.e., the milk protein casein), or sucrose solutions with low and with high essential amino acid content in concentrations as can be found in nectar. We observed micro-colonies for 110 days. We found that longevity was highest for pure pollen and lowest for pure sucrose solution and sucrose solution supplemented with amino acids in concentrations as found in the nectar of several plant species. Adding higher concentrations of amino acids to sucrose solution did only slightly increase longevity compared to sucrose alone. Consequently, sucrose solution with the applied concentrations and proportions of amino acids or other protein sources (e.g., casein) alone did not meet the nutritional needs of healthy adult bumble bees. In fact, longevity was highest and reproduction only successful in micro-colonies fed pollen. These results indicate that, in addition to carbohydrates and protein, adult bumble bees, like larvae, need further nutrients (e.g., lipids and micro-nutrients) for their well-being. An appropriate nutritional composition seemed to be best provided by floral pollen, suggesting that pollen is an essential dietary component not only for larvae but also for adult bees.

scholarly journals Arrangement of the disulphide bridges in human low-Mr kininogen

1987 ◽  
Vol 247 (1) ◽  
pp. 15-21 ◽  
Author(s):  
J Kellermann ◽  
C Thelen ◽  
F Lottspeich ◽  
A Henschen ◽  
R Vogel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Heavy Chain ◽  
Light Chain ◽  
The Other ◽  
Critical Importance

The arrangement of the disulphide bridges in human low-Mr kininogen has been elucidated. Low-Mr kininogen contains 18 half-cystine residues forming nine disulphide bridges. The first and the last half-cystine residues of the amino acid sequence form a disulphide loop which spans the heavy- and the light-chain portion of the kininogen molecule. The other 16 half-cystine residues are linked consecutively to form eight loops of 4-20 amino acids; these loops are lined up in the heavy-chain portion of the kininogen molecule. In this way, a particular pattern of disulphide loops is formed which seems to be of critical importance for the inhibitor function of human kininogen.

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