Alanine In Solution Research Articles

Behavioural responses of the Persian sturgeon (Acipenser persicus) juveniles to free amino acid solutions

This study analysed the attraction/avoidance responses of the Persian sturgeon (Acipenser persicus) juveniles to 20 free L-amino acid solutions, 0.001 M. We used aquaria with two parallel compartments with a water flow of ≈ 300 mL min−1 in each compartment. During each trial, the flow of clean water in one compartment was replaced for 3 min by a test solution of free amino acids. We counted the number of fish in each compartment every 30 s for 3 min and also used a qualitative assessment to characterise the sturgeon's searching behaviour. Daphnia water extracts were used as a positive control. Treatments and positive and negative controls (clean water) were replicated 10 times each. Solutions of alanine and glycine elicited the strongest food searching responses. This was confirmed by comparing the numbers of fish in test and control compartments. Leucine, histidine, cysteine, isoleucine and proline evoked low positive responses, which were confirmed by a quantitative assessment. Aspartic acid, tyrosine and glutamic acid evoked negative responses. The highest negative effects were evoked by glutamic acid. Therefore, alanine and glycine can be considered as attractants and glutamic acid as a repellent for Persian sturgeon juveniles.

Understanding the Chemistry of the Development of Latent Fingerprints by Superglue Fuming

Cyanoacrylate fuming is a widely used forensic tool for the development of latent fingerprints, however the mechanistic details of the reaction between the fingerprint residue and the cyanoacrylate vapor are not well understood. Here the polymerization of ethyl-cyanoacrylate vapor by sodium lactate or alanine solutions, two of the major components in fingerprint residue, has been examined by monitoring the time dependence of the mass uptake and resultant polymer molecular weight characteristics. This data provides insight into the molecular level actions in the efficient development of latent fingerprints by superglue fuming. The results show that the carboxylate moiety is the primary initiator of the polymerization process and that a basic environment inhibits chain termination while an acidic environment promotes it. The results also indicate that water cannot be the primary initiator in this forensic technique.

Optimization of fast spiral chemical shift imaging using least squares reconstruction: Application for hyperpolarized 13C metabolic imaging

A least-squares-based optimization and reconstruction algorithm has been developed for rapid metabolic imaging in the context of hyperpolarized (13)C. The algorithm uses a priori knowledge of resonance frequencies, J-coupling constants, and T(2)* values to enable acquisition of high-quality metabolic images with imaging times of approximately 100 ms for an 8-cm field of view (FOV) and 0.5 cm isotropic resolution. A root-mean-square error (rMSE) analysis is introduced to optimize metabolic image quality by appropriate choice of pulse sequence parameters, echo times, and signal model. By performing the reconstruction in k-space, the algorithm also allows the inclusion of the effect of chemical shift evolution during the readout period. Single-interleaf multiecho spiral chemical shift imaging (spCSI) is analyzed in detail as an illustrative example for the use of the new reconstruction and optimization algorithm. Simulation of the in vivo spectrum following the bolus injection of hyperpolarized (13)C(1) pyruvate shows that single-interleaf spiral spectroscopic imaging can achieve image quality in 100 ms, comparable to the performance of a 13-s phase-encoded chemical shift imaging (FIDCSI) experiment. Single-interleaf spCSI was also tested at a 3-T MR scanner using a phantom containing approximately 0.5-M solutions of alanine, lactate, and a pyruvate-pyruvate hydrate C(1)-C(2) ester at thermal equilibrium polarization, all enriched to 99% (13)C in the C(1) carbonyl positions. Upon reconstruction using the k-space-based least-squares technique, metabolite ratios obtained using the spCSI method were comparable to those obtained using a reference FIDCSI acquisition.

Nonequilibrium processes in reactions of hot tritium atoms with cooled solid targets. Attenuation of the flow of tritium atoms in adsorption layers of alkyltrimethylammonium bromides

The permeability for atomic tritium of adsorption layers of aqueous solutio ns of alkyltrimethylammonium bromides RN(CH3)3Br differing in the length of the hydrocarbon radical R (C12H25, C14H29, C16H33) was studied. The change in the radioactivity of alanine present in the examined solutions was used as the measure of the attenuation of the flow of reactive tritium atoms. The formation of an adsorption monolayer of surfactant molecules on the liquid-gas phase boundary caused the radioactivity of alanine to decrease by a factor of 6.5 (R = C12H25) to 8 (R = C16H33) relative to the experiment with a straight alanine solution. A correlation between the structure of the adsorbed layers of alkyltrimethylammonium bromides and their permeability to atomic tritium is discussed.

In situ transformation of an aqueous amino acid at high pressures and temperatures

The stability and transformation of aqueous amino acid at high pressures and temperatures are very important in terms of the formation of interstellar organic matter, delivery of organic compounds of meteorolites, and prebiotic organic synthesis. We studied aqueous alanine saturated solid solution at pressures of several gigapascals and temperatures up to 500°C using an external heating hydrothermal diamond anvil cell (HDAC) through in situ observation and Raman spectroscopy. Five samples of initial pressures of 1.23, 1.98, 2.69, 2.78, and 3.67 GPa, which cause transformation from liquid solution to solid phase, are studied. The transformations of aqueous alanine solution are highly reliant on pressure, and with higher initial pressures, the transitions are retarded to higher temperatures. The melted solid alanine solution of the lowest initial pressure separates out a non-eutectic phase which takes on the characteristic of macro-organic matter, which indicates that amino acids can oligomerize or even polymerize at high pressures and temperatures. As for the highest initial pressure, the solid alanine solution remains almost intact up to the highest temperature of 500°C. The results show that pressure should be required to understand many occurrences of amino acids in space and meteorites.

Can Raman Optical Activity Separate Axial from Local Chirality? A Theoretical Study of Helical Deca‐Alanine

Motivated by experimental work on the distinction of protein secondary structure motifs by Raman optical activity (ROA) spectroscopy, we demonstrate using density functional theory that axial chirality in structures with different local chirality can be filtered out by ROA spectroscopy. To this purpose, two diastereomers of right-handed helical deca-alanine, the (all-S) and the (R,S,R,S,R,S,R,S,R,S) form, are compared. Furthermore, we suggest to interpret calculated ROA spectra of large molecules in terms of vibrational bands rather than individual peaks. This is due to the non-homogeneous effect of the harmonic approximation as well as of the chosen electronic structure method onto the vibrational frequencies, which in a dense region of many vibrations will strongly determine the shape of the spectrum. In addition, the calculated ROA spectrum of (all-S)-deca-alanine is compared to the experimental spectrum of poly-(L)-alanine in solution.

Fast metabolic imaging of systems with sparse spectra: Application for hyperpolarized 13C imaging

A fast spiral chemical shift imaging (spCSI) sequence was developed for application to hyperpolarized (13)C imaging. The sequence exploits sparse spectra, which can occur in such applications, and prior knowledge of resonance frequencies to reduce the measurement time by undersampling the data in the spectral domain. As a consequence, multiple reconstructions of a given data set have to be computed in which only components with frequencies within a certain bandwidth are reconstructed "in focus" while others are severely blurred ("spectral tomosynthesis"). The sequence was tested at 3 T on a phantom containing approximately 1.5-M solutions of alanine (Ala), lactate (Lac), and pyruvate-pyruvate hydrate C1-C2 ester (with two resonances, PPE1 and PPE2) at thermal equilibrium polarization, all enriched to 99% (13)C in the C1 carbonyl positions. Results from spCSI with a single spatial interleaf (single-shot spCSI) and three interleaves (three-shot spCSI) were compared with those obtained by phase-encoded free induction decay CSI (FIDCSI). The metabolic maps of all four resonances for three-shot spCSI, and of PPE1 and PPE2 for single-shot spCSI demonstrate resolution and localization properties similar to those of the FIDCSI images. The metabolic maps of Ala and Lac for single-shot spCSI contain minor artifacts due to signal overlap of aliased resonances.

Thermodynamics of proton dissociations from aqueous alanine at temperatures from (278.15 to 393.15) K, molalities from (0.0075 to 1.0) mol · kg −1, and at the pressure 0.35 MPa: Apparent molar heat capacities and apparent molar volumes of alanine, alaninium chloride, and sodium alaninate

We have measured the densities of aqueous solutions of alanine, alanine plus equimolal HCl, and alanine plus equimolal NaOH at temperatures 278.15 ⩽ T/K ⩽ 368.15, at molalities 0.0075 ⩽ m/mol · kg −1 ⩽ 1.0, and at the pressure p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 ⩽ T/K ⩽ 393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes V ϕ and the heat capacities to calculate apparent molar heat capacities C p, ϕ for these solutions. We used our results and values from the literature for V ϕ ( T, m) and C p, ϕ ( T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change Δ r C p,m( T, m) for ionization of water to calculate parameters for Δ r C p,m( T, m) for the two proton dissociations from protonated aqueous cationic alanine. We integrated these results in an iterative algorithm using Young’s Rule to account for the effects of speciation and chemical relaxation on V ϕ ( T, m) and C p, ϕ ( T, m). This procedure yielded parameters for V ϕ ( T, m) and C p, ϕ ( T, m) for alaninium chloride {H 2Ala +Cl −(aq)} and for sodium alaninate {Na +Ala −(aq)} which successfully modeled our observed results. Values are given for Δ r C p,m, Δ r H m, pQ a, Δ r S m, and Δ r V m for the first and second proton dissociations from protonated aqueous alanine as functions of T and m.

Formation of peptides in the dry state

Although many potential pathways exist for the prebiotic condensation of amino acids to form simple peptides, minimal conditions for such a reaction in the dry state have yet to be defined. In this work, water was evaporated from a solution of alanine and copper chloride (CuCl 2), creating a dry residue. Incubation of this residue at moderate temperatures over 25 days produced even greater amounts of di-alanine, as determined by high performance liquid chromatographic characterization of the re-dissolved residue. Copper(II) and chloride were required for the reaction and di-peptide yields were highest for 1:2 molar ratios of copper:alanine. These results define minimal conditions for a dry-state pathway that plausibly played a role in the prebiotic formation of simple peptides.

Effect of NaBr, KCl, KBr, and MgCl2 on Viscosities of Aqueous Glycine and l-Alanine Solutions at 298.15 K

Viscosities, η, of glycine and l-alanine are measured in aqueous solutions of NaBr, KCl, KBr, and MgCl2 up to high concentrations at 298.15 K. This study suggests that 1:1 electrolytes enhance the structure-making ability of the amino acids whereas MgCl2 does not. The viscosities of the above solutions are correlated using a simple model with two interaction parameters.

Dielectric Study of Aqueous Solutions of Alanine and Phenylalanine

Dielectric relaxation measurements on aqueous solutions of alanine and phenylalanine were carried out using time domain reflectometry (TDR) at 25, 30, 35, and 40 °C in the frequency range from 10 MHz to 20 GHz. Aqueous solutions of alanine and phenylalanine are prepared for five different molar concentrations of the respective amino acid. For all the solutions considered, only one relaxation peak was observed in this frequency range. The relaxation peaks shift to lower frequency with an increase in alanine and phenylalanine molar concentration. The molar enthalpy of activation and molar entropy of activation show endothermic interactions.

Structural Changes of D1 C-terminal α-Carboxylate during S-state Cycling in Photosynthetic Oxygen Evolution

Changes in the chemical structure of alpha-carboxylate of the D1 C-terminal Ala-344 during S-state cycling of photosynthetic oxygen-evolving complex were selectively measured using light-induced Fourier transform infrared (FTIR) difference spectroscopy in combination with specific [(13)C]alanine labeling and site-directed mutagenesis in photosystem II core particles from Synechocystis sp. PCC 6803. Several bands for carboxylate symmetric stretching modes in an S(2)/S(1) FTIR difference spectrum were affected by selective (13)C labeling of the alpha-carboxylate of Ala with l-[1-(13)C]alanine, whereas most of the isotopic effects failed to be induced in a site-directed mutant in which Ala-344 was replaced with Gly. Labeling of the alpha-methyl of Ala with l-[3-(13)C]alanine had much smaller effects on the spectrum to induce isotopic bands due to a symmetric CH(3) deformation coupled with the alpha-carboxylate. The isotopic bands for the alpha-carboxylate of Ala-344 showed characteristic changes during S-state cycling. The bands appeared prominently upon the S(1)-to-S(2) transition and to a lesser extent upon the S(2)-to-S(3) transition but reappeared at slightly upshifted frequencies with the opposite sign upon the S(3)-to-S(0) transition. No obvious isotopic band appeared upon the S(0)-to-S(1) transition. These results indicate that the alpha-carboxylate of C-terminal Ala-344 is structurally associated with a manganese ion that becomes oxidized upon the S(1)-to-S(2) transition and reduced reversely upon the S(3)-to-S(0) transition but is not associated with manganese ion(s) oxidized during the S(0)-to-S(1) (and S(2)-to-S(3)) transition(s). Consistently, l-[1-(13)C]alanine labeling also induced spectral changes in the low frequency (670-350 cm(-1)) S(2)/S(1) FTIR difference spectrum.

A molecular dynamics study of the dielectric properties of aqueous solutions of alanine and alanine dipeptide.

Molecular dynamics simulations were used to compute the frequency-dependent dielectric susceptibility of aqueous solutions of alanine and alanine dipeptide. We studied four alanine solutions, ranging in concentration from 0.13-0.55 mol/liter, and two solutions of alanine dipeptide (0.13 and 0.27 mol/liter). In accord with experiment we find a strong dielectric increment for both solutes, whose molecular origin is shown to be the zwitterionic nature of the solutes. The dynamic properties were analyzed based on a dielectric component analysis into solute, a first hydration shell, and all remaining (bulk) waters. The results of this three component decomposition were interpreted directly, as well as by uniting the solute and hydration shell component to a "suprasolute" component. In both approaches three contributions to the frequency-dependent dielectric properties can be discerned. The quantitatively largest and fastest component arises from bulk water [i.e., water not influenced by the solute(s)]. The interaction between waters surrounding the solute(s) (the hydration shell) and bulk water molecules leads to a relaxation process occurring on an intermediate time scale. The slowest relaxation process originates from the solute(s) and the interaction of the solute(s) with the first hydration shell and bulk water. The primary importance of the hydration shell is the exchange of shell and bulk waters; the self-contribution from bound water molecules is comparatively small. While in the alanine solutions the solute-water cross-terms are more important than the solute self-term, the solute contribution is larger in the dipeptide solutions. In the latter systems a much clearer separation of time scales between water and alanine dipeptide related properties is observed. The similarities and differences of the dielectric properties of the amino acid/peptide solutions studied in this work and of solutions of mono- and disaccharides and of the protein ubiquitin are discussed.

Laser-based speed of sound measurements in water and aqueous D, L, and DL alanine solutions

A laser-based method for determining the speed of sound in liquids is presented in which the second harmonic (532 nm) of a pulsed Nd:YAG laser is focused into a liquid to produce a spherical sound wave pulse. A well-collimated He:Ne laser beam is positioned at a known and variable distance from the laser focus in order to determine the time-of-transit of the sound pulse. Measurements of the slope of distance versus time produces absolute values of the speed of sound in pure water within 0.06% agreement with presently accepted values. Using this method, the speed of sound in alanine/water mixtures are compared for D, L, and DL concentrations from 0 to 1.80 (saturation) molar. Isentropic compressibilities for all three solutions were determined from the measurement of sound velocity and no differences between the DL and D or L are observed, at all densities. The method is totally passive and could be used to determine sound velocities under extreme temperature or chemical conditions.

Realization of the Fredkin Gate by Three Transition Pulses ina Nuclear Magnetic Resonance Quantum Information Processor

We have experimentally realized the Fredkin gate with only three transitionpulses in a solution of alanine. It appears that no experimentalrealization of the Fredkin gate with fewer pulses has been reportedyet. In addition, the simple structure of our scheme makes it easyto implement in experiments.

Characterisation of novel 1 H ,4 H -quinolizinium-7-olate chromophores by application of colour dilution analysis and high-speed countercurrent chromatography on thermally browned pentose/ L -alanine solutions

Thermal treatment of aqueous solutions of xylose and L-alanine at pH 5.0 resulted in the formation of various coloured compounds, which were ranked according to their colour impactsby application of the recently developed colour dilution analysis. High-speed countercurrent chromatography was then successfully used for the first time to isolate colour-intense reaction products from complex Maillard mixtures, amongst which the structures of 2-[(2-furyl)methylidene]-4-hydroxy-5-methyl-2H-furan-3-one (1), and of the novel compounds 3-(2-furyl)-8-[(2-furyl)methyl]-4-hydroxymethyl-1-oxo-1H,4H-quinolizinium-7-olate (2) and 3-(2-furyl)-8-[(2-furyl)methyl]-4,5-bis(hydroxymethyl)-1-oxo-1H,4H-quinolizinium-7-olate (3) were determined by LC/MS, 1D and 2D NMR as well as UV/Vis spectroscopy. To measure the contribution of these colorants to the overall colour of the browned Maillard mixture, colour activity values were calculated as the ratio of the concentration to the visual detection threshold of each colorant. By application of this colour activity concept, 2.2% of the total colour of the thermally browned xylose/L-alanine solution was shown to be covered by the novel 1H,4H-quinolizinium-7-olate chromophores 2 and 3.

Enhancement of an Insufficient Dye-Formation in the Ninhydrin Reaction by a Suitable Post Treatment Process

A study of the reaction between ninhydrin and alanine has been carried out taking into account that, adhered on the surface of a dry porous medium such as paper, a quasi-heterogeneous reaction has to take place. Instead of amino acids released from human sweat glands, aqueous solutions of alanine were taken to deliver a given amount of amino acid to the sample. The dye density, obtained after using a standard development process, could noticeably be increased by setting a drop of water on the dye dot, thus indicating that not all the alanine had been used for dye formation during the usually applied process. The incomplete reaction can be explained by the problem of bringing the reactants into contact with each other when both are in the solid phase in the porous surrounding. The temporary presence of water allows a reorientation of the insoluble reactants. With fingerprints an increase in both the rate of development and the final dye density could be obtained when the sample was post treated after the developing process with the blank solvent, thus also the background coloration could be decreased. The ideas presented in this paper may form the basis for a modification of developing processes with ninhydrin in order to increase the proportion of amino acids present (in the sample) used in dye formation without data loss.

Spontaneous electrical potential oscillation on a filter impregnated with soybean lecithin placed between identical solutions of alanine

Filters impregnated with soybean lecithin, placed between two identical aqueous alanine solutions, display spontaneous electric potential oscillations. Alanine solutions used in a large concentration range from 1 mM to 1 M produce damped oscillatory behaviour with an exponential decay in time. The dependence of decay time on concentration shows saturation behaviour which is well fitted with a sigmoidal curve. Power spectra obtained by Fourier transform show peaks specific for each concentration. When fitted with a Lorentzian curve in the peak domain, the centre of the peak height and width at half height could be extracted. All these parameters depend on alanine concentration in a saturating pattern.

Mobilities of glycine and alanine ions in aqueous hydrochloric solutions at 25°C

By means of a multidimensional regression analysis of experimental data on the electroconductivities of aqueous hydrochloric solutions of glycine and alanine, mobilities of cations of the studied amino acids are obtained at 25°C. Conclusions are made as to various mechanisms of ionic transport in the HCl-Gly and HCl-Ala systems.

Adsorption of DL-alanine by allophane: effect of pH and unit particle aggregation

AbstractThe adsorption of DL-alanine at pH 4, 6 and 8 by a soil allophane has been determined. Two sets of experiments were carried out: (1) in which the allophane had been kept in a moist state throughout; and (2) in which the mineral had previously been dried at 50°C. In both instances, the adsorption isotherms showed three distinct regions as the concentration of alanine in solution was increased: (1) an initial, nearly linear, rise at low equilibrium concentrations; (2) a levelling off to a plateau at intermediate concentrations; and (3) a steep linear increase at high concentrations. For comparable concentrations of alanine in solution, adsorption decreased in the order pH 6 > pH 8 > pH 4. Irrespective of pH, however, more alanine was adsorbed by the ‘wet’ allophane than by its ‘dry’ counterpart. These observations are interpreted in terms of the morphology and aggregation of allophane unit particles together with the pH-dependent charge characteristics of allophane and alanine. The results are compared with published data on the adsorption of alanine by montmorillonite.