Effect Of Amino Acid Concentration Research Articles

Enhancing terahertz circular dichroism spectrum of amino acid chiral enantiomers by all-dielectric metasurface

The detection and identification of chiral substances have a wide range of applications, recently, using THz chiral spectroscopy to identify chiral biomolecules has attracted much attention. However, since the weak response, the difference between chiral enantiomers is not obvious only by THz chiral spectroscopy. To solve this problem, we combined THz time-domain polarization spectroscopy and all-dielectric metasurface to enhance the chiral spectroscopy of amino acids. The circular dichroism (CD) spectra of three pairs of amino acid chiral enantiomers were detected and compared by this method. Our results show that CD spectra of the amino acids are enhanced by the metasurface. L-Arg achieves a maximum chirality enhancement factor of 97.15 around 1 THz. For the recognition between L- and D- enantiomers, Cysteine has a maximum CD difference degree of 34.22°, which is 11.4 times higher than that without metasurface. Moreover, we also investigated the effect of amino acid concentration on chirality, founding that THz chirality was suppressed by high concentrations. Therefore, this metasurface sensor with the chiral sensing method has great potential in improving the THz chirality response of amino acids and distinguishing their chiral enantiomers with high sensitivity, which will provide new understanding and development in THz biophysics and biochemistry.

Effect of Amino Acids on Microwave Dielectric Properties of Minced Antarctic Krill (Euphausia superba)

The dielectric properties of ten solid amino acids, namely, glycine, proline, cysteine, glutamine, lysine, methionine, histidine, arginine, tyrosine, and tryptophan, and the effects of amino acid concentrations (0, 1, 3, and 5%) on the dielectric properties of minced Antarctic krill (Euphausia superba) were studied within a frequency range of 300–3000 MHz at 20.0 ± 0.5 °C. The dielectric constants and dielectric loss factor of amino acids were 2.0 ± 0.4 and 0.2 ± 0.3, respectively (moisture contents, 0.05–0.33%), except those of lysine (5.5 ± 0.5 and 1.5 ± 1.0, respectively) (moisture content, 4.5%). The dielectric properties of non-polar, neutral-polar, alkaline amino acids added to Antarctic krill were affected by the frequency and moisture contents, molecular weight, and isoelectric points (pI) of amino acids. As the molecular weight and pI values increased, the critical frequencies of aliphatic amino acid added to minced Antarctic krill decreased, whereas heterocyclic amino acid added to minced Antarctic krill increased. Quantitative relationships between parameters that define both the real and the imaginary parts of the Debye relations and the weight fraction of amino acid contents in Antarctic krill were determined. Moreover, glycine (at 5%) or lysine (at 5%) significantly influenced the dielectric constants and dielectric loss factor of minced Antarctic krill (p < 0.05) but did not have significant effects on temperature history and distribution (p < 0.05) during microwave heating at 2450 MHz.

Effect of Biofriendly Amino Acids on the Kinetics of Methane Hydrate Formation and Dissociation

Solidified natural gas (SNG) is a promising option to store natural gas in the form of clathrate hydrates because of several benefits offered that include high degree of safety, eco-friendliness, high volumetric storage capacity, and the relative ease of gas recovery. Environmentally benign amino acids have been reported as promising kinetic promoters for enhancing methane hydrate formation. In this work, we examine in detail the effect of three different types of amino acids—tryptophan (nonpolar, hydrophobic amino acid with aromatic side chain), histidine (polar, basic amino acid with aromatic side chain), and arginine (polar, basic amino acid with aliphatic side chain)—on the kinetics of methane hydrate formation. The effect of amino acid concentration on the hydrate formation kinetics was investigated in two reactor configurations, namely, stirred and unstirred tank reactors. Amongst the amino acids studied, the best kinetic promotion for methane hydrate formation (in both stirred and unstirred reactor...

Extended studies on molecular interactions of SDBS and DTAB in aqueous solutions of amino acid at T = 293.15–313.15 K

The volumetric properties for this mixture of amino acid–surfactant system have already been discussed in an earlier published article, but to go further into the details on molecular interactions, different acoustical parameters viz. relative association (RA), intermolecular free length (Lf), molar sound number ([U]), specific acoustic impedance (Z), free volume (Vf), molar volume (Vm), internal pressure (πi) and molar cohesive energy (MCE) have been evaluated from the parent data of density, speed of sound and viscosity. The variation of these parameters with concentration of surfactant helps us in understanding the nature and extent of interactions present among the molecules in the mixture. The effect of amino acid concentrations on the micellization behavior of these surfactants has also been discussed through these parameters.

A comparison of digestible amino acid databases: Relationship between amino acid concentration and digestibility

SUMMARY Databases compiling the amino acid (AA) digestibility values of 20 common poultry feed ingredients from 2 commercial companies, Evonik Degussa (Burr Ridge, IL; chick assays) and Ajinomoto Heartland (Chicago, IL; rooster assays), were used to investigate the influence of AA concentration on observed digestibility values. Casual observation of the rooster assay database suggested that AA digestibility may be related to AA concentration. Ideally, digestibility should be a property of the feed ingredient and should not be related to the concentration at which an ingredient is fed. If the AA concentration during an assay has a large effect on its digestibility, then the results may not be valid at different levels of feed ingredients or when the AA concentration in the test situation is different from actual feeding levels in a diet. Differences in digestibility values in the Evonik Degussa and Ajinomoto Heartland databases were compared. Multiple regression techniques were then used to test the hypothesis that the results of the AA digestibility assays were related to the AA concentration in the feed ingredient being tested. Total AA concentration and digestible AA averaged 6 and 14% higher in the rooster database than in the chick database, respectively. Differences in assay type were quantitative because slopes of digestible AA = f(total AA concentration) were positive for 19 of 20 ingredients in each database. However, when all data were included in 1 model, the influence of concentration on digestibility was very unlikely to have been due to chance (P < 0.0006), as evidenced by the interaction of concentration × assay type. Removing the lowest (Trp) or highest (Ile) AA was not critical to the conclusions. The effect of AA concentration on its digestibility was quantitatively the same for each AA (P < 0.50) except Cys (P < 0.05). We confirmed, based on data from the 3 selected articles, that this relationship was not due only to the different samples in the different databases. Therefore, to best predict the digestibility of any AA in any ingredient, its intended concentration in the diet should be known.

Spectrofluorometric analysis of amino acid mixtures: Implications for future space missions

Efficient detection of organic molecules is fundamental for the success of future life detection missions. Spectrofluorometric analysis is one of the many techniques that may be used to detect organic molecules in extraterrestrial settings. A particularly important class of organic molecules to target is the amino acids on which all terrestrial life depends. This study aims to identify the optimum fluorescence excitation and emission wavelengths for 17 amino acid standards to examine the effects of amino acid concentrations, mixtures and fluorescence quenching. The results and interpretations can guide the design and operation of life detection protocols on future space missions.

Effect of Amino Acid Concentration on Orotic Acid Production by Bovine Mammary Tissue

Investigations were to determine if bovine mammary tissue could synthesize orotate and to assess the influence of amino acids on production of orotate. Mammary tissue from 6 Holstein cows was obtained immediately after slaughter. Tissue slices were incubated in either a modified Krebs-Ringer bicarbonate buffer, the same medium containing a physiological concentration of amino acids, or a third medium containing a fourfold concentration of the amino acid mixture. In all experiments, tissue slices were preincubated in the physiological amino acid medium for 5, 10, and 15min (30 total min) with fresh medium changes after each incubation interval. Tissue slices then were incubated with one of the three treatment media for three consecutive 20-min periods. Tissue slices incubated in the physiological amino acid medium for a total of 90min synthesized 28.5µg orotate/g wet tissue after correction for the initial tissue contribution. Orotate secreted by the tissue slices increased as concentration of amino acids increased. Lactose released into the medium was not affected by amino acid concentration. Bovine mammary tissue can synthesize substantial amounts of orotate, and tissue syndiesis of orotate but not lactose increased as amino acid concentration increased.

The effect of amino acids on the temperature sensitive phenotype of the mammalian leucyl‐tRNA synthetase mutant ts Hl and its revertants

The temperature sensitive leucyl-tRNA synthetase mutant tsHl and two revertants have been compared to the parental Chinese hamster ovary cells with respect to the effects of amino acid concentrations in the medium on growth. Elevating the leucine concentration 30- or 100-fold allowed tsHl to grow exponentially at 38.5 degrees C, normally the nonpermissive temperature. Partial revertants that had recovered some enzyme activity required smaller supplements for growth. Measurements of the leucine pools indicated that they respond directly to the extracellular leucine concentration and may mediate the effect. Use of combinations of amino acids confirmed that isoleucine has a similar though weaker effect on tsHl and identified an even weaker protection by valine. The triple combination of leucine, isoleucine and valine was a much more efficient medium supplement and three times normal concentrations of these amino acids supported growth of tsHl at 38.5 degrees C. It is postulated that they are acting at their respective aminoacyl-tRNA synthetases to help stabilize a complex which also contains the mutant leucyl-tRNA synthetase. The pool size measurements also showed that the leucine pools of tsHl and a revertant increased 2-fold more in a response to increased temperature than those of WT. It is suggested that this is a regulatory response to low leucyl-tRNA synthetase activity and is important in determining growth phenotypes.

Lack of effect of amino acid concentration on protein synthesis in the perfused rat liver.

The effect of increasing the perfusate concentration of amino acids on the incorporation of labelled valine into protein was followed in perfusions of rat livers lasting for 2h. A fixed amount of labelled and unlabelled valine was added to the perfusate as the other amino acids were increased in multiples of the concentrations normally found in rat plasma. Under these conditions no increase in valine incorporation was observed, which appeared to be in conflict with results published by other workers, However, a different method of labelling from that used here was used in the earlier studies. An increasing amount of a labelled amino acid was added as the concentrations of the unlabelled amino acids were increased in the perfusate. An experiment directly comparing to the two labelling methods produced results that indicated that the apparent increase in liver protein synthesis observed by the other workers could have been due to the method of radioisotope addition. It is therefore concluded that increasing the perfusate concentration of amino acids does not increase amino acid incorporation into liver protein.

Studies on contact inhibition of growth in the mouse fibroblast, 3T3. II. Effects of amino acid deprivation and serum on growth rate.

ABSTRACT The effect of amino acid concentration on the initial growth rate of the contact-inhibited mouse fibroblasts 3T3 and its SV40-transformed derivative 3T3T has been studied. In medium in which the serum had been passed through a Sephadex column, and the concentration of amino acids lowered 1000-fold, one acid at a time, the growth rate constants were computed. For most of the 16 amino acids studied, the initial growth rate of 3T3 decreased more profoundly than that of 3T3T. The presence in serum of a factor which stimulates amino acid uptake and growth rate of 3T3T is described.

Effect of abnormal amino acid concentrations on blood-brain barrier.

Nachweis, dass die i.p. Injektion grosser Mengen vonl-Tyrosin die Permeabilitat der hypothetischen «Blut-Hirn-Schranke» betrachtlich herabsetzt. Pyridoxalphosphat verhindert nicht nur diese Hemmung, sondern steigert die Absorption vonl-Lysin.

Studies on growth hormone. IV. The effects of changing amino acid concentrations upon the hormonal regulation of protein metabolism in the isolated, perfused liver.

Abstract The effects of GH and insulin upon the metabolism of perfused rabbit liver are altered considerably by changes in the perfusate amino acid levels. Thus, with physiologic levels of amino acids and in contrast to the "high-level" experiments: 1.1. GH no longer decreases urea production, but actually increases it. 2.2. Insulin decreases urea production. 3.3. GH produces a rising amino acid level, and insulin produces a falling amino acid concentration. These effects are directionally in agreement with the high-level results; however, the low-level GH curve ascends to a plateau while the high-level GH curve descends to its plateau. 4.4. Both GH and insulin-induced C 14 perfusate protein activity were much closer to control levels than in the presence of high alpha amino nitrogen concentrations. 5.5. The directional effects of both hormones on perfusate glucose concentrations were independent of amino acid concentration, insulin causing hyperglycemia and GH hypoglycemia. These effects on the isolated liver are directly opposite to those seen following the administration of these hormones to intact animals. 6.6. The results indicate that GH increases amino acid and protein turnover rates with low-substrate levels, while decreasing them with high levels. In contrast, insulin acts to slow amino acid and protein turnover at low alpha amino acid levels, and speed it (relative to both GH and controls) at high levels. Various facets of this interesting relationship are discussed.