Alkyl Chain Of Amino Acids Research Articles

Temperature and concentration dependence towards physicochemical and FTIR spectral studies of glycine, L-alanine and L-valine in aqueous solutions of nortriptyline hydrochloride

Apparent and partial molar properties for glycine, L-alanine and L-valine in aqueous solutions (0.025–0.075) mol·kg−1 of drug NTPH (nortriptyline hydrochloride) have been reported in the present study at intervals of 5 K from temperature 288.15 K to 308.15 K and at experimental pressure of p=0.1 MPa. Different parameters viz. transfer partial molar properties, hydration numbers (nH), partial molar expansibility (E∅0), isobaric thermal expansion coefficient (α) and Hepler’s constant, calculated by using the experimental data of density (ρ) and ultrasonic speeds (u) predict that the solute-solvent interactions are dominating in these ternary systems. The linear variation of V∅0 with the number of carbon atoms in the alkyl chain of amino acids has been utilized to calculate the contribution of the charged end groups NH3+,COO-, (CH2) group and other alkyl chains of the amino acids to V∅0. Pair and triplet interaction coefficients determined from ΔV∅0 and ΔK∅,s0 values using McMillan-Mayer theory indicate the dominance of pairwise interactions in the studied ternary mixtures. The hydration number (nH) comes out to be positive suggesting strong dehydration effect of NTPH. FTIR spectra have been recorded for the mixtures of amino acids in aqueous solutions of NTPH. The decrease in wave number of N–H stretching band also suggests the structural changes in these systems.

Investigations on molecular interaction of some amino acids with the drug levofloxacin in aqueous solution by volumetric and acoustic methods at different temperatures

Apparent molar properties (V∅ and K∅,s) of amino acids (glycine, L-alanine and L-valine) within the concentration range of (0.02–0.20)mol·kg−1inaqueous (0.005, 0.01and0.03)mol·kg−1 Levofloxacin (LVFX) solutions are computed from the experimental density (ρ) and ultrasonic speed (c) values at T=(288.15, 293.15, 298.15, 303.15and308.15)K and P=0.1MPa. Derived parameters such as partial molar properties (V∅0 and K∅,s0) and their experimental slopes (SV and SK), transfer partial molar properties (ΔV∅0 and ΔK∅,s0), hydration numbers (nH) and Hepler’s constant are computed from the data of apparent molar properties. The pair and triplet interaction coefficients have also been evaluated from transfer parameters. The linear variation of V∅0 with the number of carbon atoms in the alkyl chain of amino acids has been utilized to calculate the contribution of the charged end groups (NH3+,COO-), (CH2) group and other alkyl chains of the amino acids to V∅0. From the obtained parameters, some information in regard with the solute-solvent interaction in the systems studied was obtained. The co-sphere overlap model was used to interpret the positive transfer properties (ΔV∅0 and ΔK∅,s0). The volume and compression data suggest that there exist strong solute-solvent interactions in these systems, which increase with increase in temperature. It is inferred that amino acids studied act as structure-breaker (chaotropic effect) in aqueous LVFX solutions.

Investigation on solute–solvent interactions of glycine, l-alanine and l-valine in aqueous tetraethylammonium iodide solutions at different temperatures with reference to volumetric and acoustic measurements

The interactions of amino acids glycine, l-alanine and l-valine with tetraethylammonium iodide (TEAI) as a function of temperature have been investigated by a combination of volumetric and acoustic measurement. Densities (ρ) and ultrasonic speeds (u) of amino acids in aqueous solutions of TEAI have been measured at T=(288.15, 293.15, 298.15, 303.15 and 308.15)K and p=0.1MPa. The apparent molar volume (V∅), the partial molar volume (V∅0) and standard partial molar volumes of transfer (ΔV∅0) for amino acids from water to aqueous TEAI solutions have been calculated from density values. Apparent molar isentropic compressibility (K∅,s), partial molar isentropic compressibility (K∅,s0), partial molar isentropic compressibility of transfer (ΔK∅,s0) have been calculated from values of the ultrasonic speed. The pair and triplet interaction coefficients have been calculated from both properties. The linear variation of V∅0 with the number of carbon atoms in the alkyl chain of amino acids has been utilized to calculate the contribution of the charged end groups (NH3+,COO-), (CH2) group and other alkyl chains of the amino acids to V∅0. The results obtained are discussed in the light of various interactions operating in ternary systems of amino acids, water and TEAI.

Partial molar adiabatic compressibilities of transfer of some amino acids from water to aqueous lactose solutions at different temperatures

Apparent molar adiabatic compressibilities ( K ϕ, s ) of glycine, L-alanine, L-valine, and L-leucine have been determined in aqueous and mixed aqueous solutions of lactose (2 to 6 mass%) at T = (293.15, 298.15, 303.15, and 308.15) K. From these data partial molar adiabatic compressibilities at infinite dilution ( K ϕ, s 0) have been evaluated to calculate corresponding transfer function. The transfer partial molar adiabatic compressibilities at infinite dilution ( ΔK ϕ, s 0) are found to be positive. The decrease in the magnitude of transfer partial molar adiabatic compressibilities from glycine to L-leucine indicates the dominance of hydrophobic–hydrophobic interactions between the increasing side chains of amino acids. Also, the contributions of NH 3 + COO − , and CH 2 groups have been calculated by the linear correlation of K ϕ, s 0 with number of carbon atoms in the alkyl chain of amino acids.

Volumetric behaviour of amino acids and their group contributions in aqueous lactose solutions at different temperatures

Densities, ρ, for glycine, l-alanine, l-valine, and l-leucine [(0.05 to 0.30) m] in aqueous lactose solutions ranging from pure water to 6 mass% lactose were determined at T = (293.15, 298.15, 303.15, and 308.15) K. The density was used to compute apparent molar volume, V φ , partial molar volume at infinite dilution, V ϕ o , and experimental slope, S V were obtained and interpreted in terms of solute–solvent and solute–solute interactions. These data were used to calculate the ( ∂ V ϕ 0 / ∂ T ) P values. The partial molar volume of transfer, Δ V ϕ 0 from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of V ϕ 0 with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH 3 + COO - , and CH 2 groups to V ϕ 0 .

Volumetric properties of amino acids in aqueous solution of nonionic surfactant

The volumetric properties of amino acids ( dl-glycine, dl-alanine, dl-serine, l-aspartic acid, l-lysine, and l-leucine) in aqueous solution of nonionic surfactant hexadecyl poly[oxyethylene(25)] alcohol (C 16A 25) are studied. The values of apparent molar volumes V ϕ , partial molar volumes V 2 , m 0 and volumes of transfer Δ t 2 V 2 , m 0 are calculated. The changes of volumes of transfer are discussed in terms of hydrophilic–hydrophobic interactions. The linear correlation of V 2 , m 0 for a amino acids is utilized to calculate the contribution of the charge groups ( N H 3 + , CO O − ) , CH 2 group and other alkyl chains of amino acids to V 2 , m 0 .

Molecular interactions of selected amino acids in aqueous resorcinol solutions: volumetric, viscometric and acoustic studies

Apparent molar volumes, Vo,, viscosities, η, and apparent molal isentropic compressibility, K o, , of glycine, L-alanine, L-valine and L-leucine in 0.05, 0.10, 0.15 mol kg -1 resorcinol solutions have been determined at 298.15 K by measuring the densities, viscosities and ultrasonic speed of the above solutions respectively. The apparent molar volumes at infinite dilution, V o 0 , standard volumes of transfer, ΔtrV o 0 , apparent molar isentropic compressibilities, K o 0 , transfer compressibilities, ΔtrKo 0 , hydration number, N w , of the amino acids have been calculated for investigating the various interactions in the ternary solutions. The linear correlation of partial molar volume and viscosity Bcoefficients with increasing number of carbon atoms in the alkyl chain have been utilized to calculate the contributions of charged end groups (NH 3 + ,COO - ), CH 2 - groups and other alkyl chains of amino acids to V o 0 . The results have been interpreted in terms of ion-ion, ion-polar, hydrophilic-hydrophilic and hydrophobichydrophobic group interactions in the mixed ternary solutions.

Volumetric and Viscometric Behaviour of some Amino Acids and their Group Contributions in Aqueous Tetramethylammonium Bromide at Different Temperatures

Abstract Densities, ρ and viscosities, η for L-serine, L-threonine, L-glutamine, L-lysine, L-arginine and L-histidine (0.05–0.25 m) in 0.20 m aqueous tetramethylammonium bromide were determined at 298.15, 303.15, 308.15, and 313.15 K. The density data was used to compute apparent molar volume, φ v . The partial molar volume, φ v 0, at infinite dilution and experimental slope, S v * were obtained from Masson´s equation and interpreted in terms of solute-solvent and solute-solute interactions, respectively. The φ v 0 values are found to vary with temperature as a power series of temperature. The structure-making/-breaking ability of solute were discussed using Hepler´s criterion. The partial molar volumes of transfer, φ v 0 (tr) of amino acid from aqueous to aqueous tetramethylammonium bromide solution were interpretedin the light of cosphere overlap model. The viscosity data was utilized to determine A- and B-coefficients of viscosity, free energy of activation of viscous flow, Δμ 1 0 * and Δμ 2 0 *, per mole of solvent and solute, respectively, and ΔH * and ΔS * were also evaluated. The linear variation of φ v 0 and B-coefficient with the number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of (NH3 +, COO–) and CH2 groups to φ v 0 and B-coefficient, respectively.

Volumetric and Refractive Index Behaviour of α-Amino Acids in Aqueous CTAB at Different Temperatures

Densities (ρ) and refractive indices ( n D) of glycine (Gly), DL-alanine (Ala), DL-valine (Val) (0.02, 0.04, 0.06, 0.08, and 0.10 mol·L −1) in 0.005 and 0.008 mol·L −1 aqueous cetyltrimethylammonium bromide (CTAB) have been measured at 298.15, 303.15, 308.15, and 313.15 K. The density data have been utilized to calculate apparent molar volumes (ϕ v), partial molar volumes (ϕ v 0), at infinite dilution and partial molar volumes of transfer ϕ v 0(tr) of amino acids. The refractive index data have been used to calculate molar refractivity ( R D) of amino acids in aqueous cetyltrimethylammonium bromide. It has been observed that ϕ v 0 varies linearly with increasing number of carbon atoms in the alkyl chain of amino acids, and hence, was split to get contributions from the zwitterionic end groups (NH 3 +, COO −) and methylene group (CH 2) of the amino acids. The behaviour of these parameters has been used to investigate the solute-solute, solute-solvent interactions and the effect of cetyltrimethylammonium cation on these interactions.

Volumetric, viscometric and refractive index behavior of some α-amino acids in aqueous tetrapropylammonium bromide at different temperatures

Densities, ρ, viscosities, η, and refractive indices, nD, of glycine (Gly), DL-alanine (Ala), DL-valine (Val) (0.05, 0.10, 0.15, 0.20, 0.25 mol kg−1), and L-leucine (Leu) (0.02, 0.05, 0.10 mol kg−1) in water and in 0.20 mol kg−1 aqueous tetrapropylammonium bromide (TPAB) have been measured at 298.15, 303.15, 308.15, and 313.15 K. The density data have been utilized to calculate apparent molar volumes, ϕv, partial molar volumes at infinite dilution, ϕv°, and partial molar volumes of transfer, ϕv°(tr) of amino acids. The viscosity data have been analyzed by means of Jones-Dole equation to obtain Falkenhagen coefficient, A, and Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δµ1°*, and solute, Δµ2°*, and enthalpy, ΔH*, and entropy of activation, ΔS*, of viscous flow. The refractive index data have been used to calculate molar refractivity, RD, of amino acids in aqueous tetrapropylammonium bromide solutions. It has been observed that ϕv°, B-coefficient and Δµ2°* vary linearly with increasing number of carbon atoms in the alkyl chain of amino acids, and they were split to get contributions from the zwitterionic end groups (NH3+, COO-) and methylene group (CH2) of the amino acids. The behavior of these parameters has been used to investigate the solute-solute and solute-solvent interactions as well as the effect of tetrapropylammonium cation (C3H7)4N+ on these interactions.

Partial Molar Volumes of Some of α-Amino Acids in Binary Aqueous Solutions of MgSO4·7H2O at 298.15 K

The apparent molar volume, V o φ,2, of glycine, alanine, α-amino-n-butyric acid, valine and leucine have been determined in aqueous solutions of 0.25, 0.5 and 1.0 mol·dm −3 magnesium sulfate, and the partial specific volume from density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volume, V o 2,m , group contribution of amino acids and partial molar volume of transfer, � trV o 2,m , from water to aqueous magnesium sulfate solutions. The linear correlation of V o 2,m for a homologous series of amino acids has been utilized to calculate the contributions of charged end groups (NH + , COO − ), CH2- groups and other alkyl chains of amino acids to V o 2,m . The results fortrV o 2,m of amino acids from water to aqueous magnesium sulfate solutions have been interpreted in terms of ion-ion, ion-polar, hydrophilic-hydrophilic and hydrophobic-hydrophobic group interactions. The values of the standard partial molar volume of transfer for the amino acids with different hydrophobic contents, from water to aqueous MgSO4 are in general positive, indicating the predominance of the interactions of zwitterionic/hydrophilic groups of amino acids with ions of the salt. The hydration number decreases with increasing concentration of salt. The number of water molecules hydrated to amino acids decreases, further strengthening the predominance of ionic/hydrophilic interactions in this system.

Enthalpic interaction for a‐amino acid with alkali metal halides in water

AbstractThe studies of the enthalpic interaction parameters, hxy, hxyy and hxyy of alkali metal halides with glycine, α‐alanine and a‐aminobutyric acid were published. Synthetic considering of the results of the studies, some interesting behaviors of the interaction between alkali metal halides and the a‐amino acids have been found. The values of hxy will increase with the increase of the number of carbon atoms in alkyl side chain of amino acid molecules and decrease with the increase of the radius of the ions. The increasing of the salt's effect on the hydrophobic hydration structure as the radii of anion is more obvious than as that of cation. The value of hxxy will regularly decrease with the increase of the number of carbon atoms in the alkyl chain of amino acids and linear increase with the increase of the radius. But the relation of hxxy with the radius of cations is not evident. The value of hxyy will increase with the increase of the radii of the ions. As the increase of the number of carbon atom of amino acids, hxyy is decreas for the ions which have lager size and there is a maximum value at α‐aniline for the ions which have small she. The behaviors of the interaction mentioned above were further discussed in view of electrostatic and structural interactions.