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Carmen M Romero - One of the best experts on this subject based on the ideXlab platform.
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A comparative study between the behavior diffusion of α-Aminobutyric Acid and γ-Aminobutyric Acid in sodium chloride aqueous solutions
Journal of Molecular Liquids, 2019Co-Authors: Maria M. Rodrigo, Miguel A Esteso, Luis M P Verissimo, Carmen M Romero, M L Ramos, Artur J.m. Valente, Ana C F RibeiroAbstract:Abstract Ternary mutual diffusion coefficients measured by the Taylor dispersion method are reported for two aqueous systems, that is, DL-2-Aminobutyric Acid (AABA) + sodium chloride, and DL-4-Aminobutyric Acid (GABA) + sodium chloride at 298.15 K, and at different carrier concentrations (from 0 to 0.010 mol dm−3). These data, complemented by NMR measurements, permit us to have a better understanding of the structure of these ternary systems, and their thermodynamic and transport behaviour. The effect of the ionic strength on the transport properties of both amino Acids has been assessed. Contrary to AABA, the presence of sodium chloride does not affect the structure of GABA and its diffusion properties. This has been justified by the preferential intramolecular electrostatic interaction between ammonium and carboxylate groups.
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diffusion and structural behaviour of the dl 2 Aminobutyric Acid
The Journal of Chemical Thermodynamics, 2019Co-Authors: Melia M Rodrigo, Miguel A Esteso, Luis M P Verissimo, Carmen M Romero, M L Ramos, Licinia L G Justino, Hugh D Burrows, Ana C F RibeiroAbstract:Abstract dl -2-Aminobutyric Acid (α-Aminobutyric Acid or AABA) is a non-protein amino Acid with important physiological properties, and with considerable relevance in different areas, such as fundamental research and pharmaceutical industry. In this paper, the binary mutual diffusion coefficients of AABA in non-buffered aqueous solutions (0.001–0.100) mol·dm−3 at 298.15 K were measured. From these diffusion data, limiting values at infinitesimal concentration, D0, as well as those of the thermodynamic factors, FT, and activity coefficients, γ, were estimated. These data for AABA were compared with the data previously obtained for dl -4-Aminobutyric Acid (GABA). The difference of the behaviour of these transport properties for both amino-Acids was explained based on the structural differences for the monomeric zwitterionic species of AABA and GABA. Such structural differences are supported by both 1H and 13C NMR spectroscopy and theoretical calculations, which indicate that the predominant species of AABA in these solutions is the extended zwitterionic form in contrast with the curled one of GABA.
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Surface Tension of Glycine, Alanine, Aminobutyric Acid, Norvaline, and Norleucine in Water and in Aqueous Solutions of Strong Electrolytes at Temperatures from (293.15 to 313.15) K
Journal of Chemical & Engineering Data, 2017Co-Authors: Diana M Rodriguez, Carmen M RomeroAbstract:The surface tension of glycine, alanine, 2-Aminobutyric Acid (AABA), norvaline, and norleucine in water and in aqueous solutions of five strong electrolytes (LiCl, NaCl, KCl, (NH4)2SO4, and Na2SO4) was determined in the temperature range between 293.15 and 313.15 K with a LAUDA TVT2 tensiometer using the drop volume method. As the temperature rises, the surface tension decreases as the cohesion between molecules becomes weaker. The limiting slopes of the surface tension as a function of mole fraction of the amino Acids in water show that glycine and alanine are hydrophilic solutes whereas α-Aminobutyric Acid, norvaline, and norleucine behave as hydrophobic solutes, and this behavior is not affected by the addition of the salts. The presence of electrolytes increases the surface tension of the α-amino Acid solutions; however, it is not possible to classify the effect of the anions and cations on this property because the surfaces of the mixed solvents are different and a comparison between them is not pert...
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Ionization Constants of DL-2-Aminobutyric Acid and DL-Norvaline Under Hydrothermal Conditions by UV–Visible Spectroscopy
Journal of Solution Chemistry, 2017Co-Authors: Daniel E. Nieto Roca, Carmen M Romero, Peter R. TremaineAbstract:The first and second ionization constants for the amino Acids DL-2-Aminobutyric Acid (DL-2-aminobutanoic Acid) and DL-norvaline (DL-2-aminopentanoic Acid) were determined under hydrothermal conditions, from 175 to 275 °C at 10 MPa, using thermally-stable colorimetric pH indicators (acridine, 4-nitrophenol and 2-naphthoic Acid). The measurements were carried out by UV–visible spectroscopy using a high-temperature, high-pressure platinum flow cell with sapphire windows, which minimized the effects of thermal decomposition. The results were combined with literature values from titration calorimetry at 25–130 °C to yield an extended van’t Hoff model for the temperature dependence of the ionization constants for the carboxylic Acid and ammonium groups, $$ K_{\text{a,COOH}} $$ K a,COOH and $$ K_{{{\text{a,NH}}_{3}^{ + } }} $$ K a,NH 3 + , over the entire temperature range. The experimental results for the second ionization constant $$ K_{{{\text{a,NH}}_{3}^{ + } }} $$ K a,NH 3 + at elevated temperatures are consistent with the predictions from the Yezdimer–Sedlbauer–Wood functional group additivity model, but for the first ionization constant $$ K_{\text{a,COOH}} $$ K a,COOH are not. This suggests that the group contribution parameters for the standard partial molar heat capacity of the carboxylic Acid group are in error, or that nearest neighbor interactions between the –COOH and $$ - {\text{NH}}_{3}^{ + } $$ - NH 3 + groups cause a breakdown in the functional group additivity relationship.
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effect of temperature on the partial molar volume isentropic compressibility and viscosity of dl 2 Aminobutyric Acid in water and in aqueous sodium chloride solutions
The Journal of Chemical Thermodynamics, 2017Co-Authors: Carmen M Romero, Ana C F Ribeiro, Diana M Rodriguez, Miguel A EstesoAbstract:Abstract Density, sound velocity and viscosity of DL-2-Aminobutyric Acid in water and in aqueous sodium chloride solutions have been measured at temperatures of (293.15, 298.15, 303.15, 308.15 and 313.15) K. The experimental results were used to determine the apparent molar volume and the apparent molar compressibility as a function of composition at these temperatures. The limiting values of both the partial molar volume and the partial molar adiabatic compressibility at infinite dilution of DL-2-Aminobutyric Acid in water and in aqueous sodium chloride solutions were determined at each temperature. The experimental viscosity values were adjusted by a least-squares method to a second order equation as proposed by Tsangaris-Martin to obtain the viscosity B coefficient which depends on the size, shape and charge of the solute molecule. The influence of the temperature on the behaviour of the selected properties is discussed in terms of both the solute hydration and the balance between hydrophobic and hydrophilic interactions between the Acids and water, and the effect of the sodium chloride concentration.
Miguel A Esteso - One of the best experts on this subject based on the ideXlab platform.
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A comparative study between the behavior diffusion of α-Aminobutyric Acid and γ-Aminobutyric Acid in sodium chloride aqueous solutions
Journal of Molecular Liquids, 2019Co-Authors: Maria M. Rodrigo, Miguel A Esteso, Luis M P Verissimo, Carmen M Romero, M L Ramos, Artur J.m. Valente, Ana C F RibeiroAbstract:Abstract Ternary mutual diffusion coefficients measured by the Taylor dispersion method are reported for two aqueous systems, that is, DL-2-Aminobutyric Acid (AABA) + sodium chloride, and DL-4-Aminobutyric Acid (GABA) + sodium chloride at 298.15 K, and at different carrier concentrations (from 0 to 0.010 mol dm−3). These data, complemented by NMR measurements, permit us to have a better understanding of the structure of these ternary systems, and their thermodynamic and transport behaviour. The effect of the ionic strength on the transport properties of both amino Acids has been assessed. Contrary to AABA, the presence of sodium chloride does not affect the structure of GABA and its diffusion properties. This has been justified by the preferential intramolecular electrostatic interaction between ammonium and carboxylate groups.
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diffusion and structural behaviour of the dl 2 Aminobutyric Acid
The Journal of Chemical Thermodynamics, 2019Co-Authors: Melia M Rodrigo, Miguel A Esteso, Luis M P Verissimo, Carmen M Romero, M L Ramos, Licinia L G Justino, Hugh D Burrows, Ana C F RibeiroAbstract:Abstract dl -2-Aminobutyric Acid (α-Aminobutyric Acid or AABA) is a non-protein amino Acid with important physiological properties, and with considerable relevance in different areas, such as fundamental research and pharmaceutical industry. In this paper, the binary mutual diffusion coefficients of AABA in non-buffered aqueous solutions (0.001–0.100) mol·dm−3 at 298.15 K were measured. From these diffusion data, limiting values at infinitesimal concentration, D0, as well as those of the thermodynamic factors, FT, and activity coefficients, γ, were estimated. These data for AABA were compared with the data previously obtained for dl -4-Aminobutyric Acid (GABA). The difference of the behaviour of these transport properties for both amino-Acids was explained based on the structural differences for the monomeric zwitterionic species of AABA and GABA. Such structural differences are supported by both 1H and 13C NMR spectroscopy and theoretical calculations, which indicate that the predominant species of AABA in these solutions is the extended zwitterionic form in contrast with the curled one of GABA.
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effect of temperature on the partial molar volume isentropic compressibility and viscosity of dl 2 Aminobutyric Acid in water and in aqueous sodium chloride solutions
The Journal of Chemical Thermodynamics, 2017Co-Authors: Carmen M Romero, Ana C F Ribeiro, Diana M Rodriguez, Miguel A EstesoAbstract:Abstract Density, sound velocity and viscosity of DL-2-Aminobutyric Acid in water and in aqueous sodium chloride solutions have been measured at temperatures of (293.15, 298.15, 303.15, 308.15 and 313.15) K. The experimental results were used to determine the apparent molar volume and the apparent molar compressibility as a function of composition at these temperatures. The limiting values of both the partial molar volume and the partial molar adiabatic compressibility at infinite dilution of DL-2-Aminobutyric Acid in water and in aqueous sodium chloride solutions were determined at each temperature. The experimental viscosity values were adjusted by a least-squares method to a second order equation as proposed by Tsangaris-Martin to obtain the viscosity B coefficient which depends on the size, shape and charge of the solute molecule. The influence of the temperature on the behaviour of the selected properties is discussed in terms of both the solute hydration and the balance between hydrophobic and hydrophilic interactions between the Acids and water, and the effect of the sodium chloride concentration.
Ana C F Ribeiro - One of the best experts on this subject based on the ideXlab platform.
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A comparative study between the behavior diffusion of α-Aminobutyric Acid and γ-Aminobutyric Acid in sodium chloride aqueous solutions
Journal of Molecular Liquids, 2019Co-Authors: Maria M. Rodrigo, Miguel A Esteso, Luis M P Verissimo, Carmen M Romero, M L Ramos, Artur J.m. Valente, Ana C F RibeiroAbstract:Abstract Ternary mutual diffusion coefficients measured by the Taylor dispersion method are reported for two aqueous systems, that is, DL-2-Aminobutyric Acid (AABA) + sodium chloride, and DL-4-Aminobutyric Acid (GABA) + sodium chloride at 298.15 K, and at different carrier concentrations (from 0 to 0.010 mol dm−3). These data, complemented by NMR measurements, permit us to have a better understanding of the structure of these ternary systems, and their thermodynamic and transport behaviour. The effect of the ionic strength on the transport properties of both amino Acids has been assessed. Contrary to AABA, the presence of sodium chloride does not affect the structure of GABA and its diffusion properties. This has been justified by the preferential intramolecular electrostatic interaction between ammonium and carboxylate groups.
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diffusion and structural behaviour of the dl 2 Aminobutyric Acid
The Journal of Chemical Thermodynamics, 2019Co-Authors: Melia M Rodrigo, Miguel A Esteso, Luis M P Verissimo, Carmen M Romero, M L Ramos, Licinia L G Justino, Hugh D Burrows, Ana C F RibeiroAbstract:Abstract dl -2-Aminobutyric Acid (α-Aminobutyric Acid or AABA) is a non-protein amino Acid with important physiological properties, and with considerable relevance in different areas, such as fundamental research and pharmaceutical industry. In this paper, the binary mutual diffusion coefficients of AABA in non-buffered aqueous solutions (0.001–0.100) mol·dm−3 at 298.15 K were measured. From these diffusion data, limiting values at infinitesimal concentration, D0, as well as those of the thermodynamic factors, FT, and activity coefficients, γ, were estimated. These data for AABA were compared with the data previously obtained for dl -4-Aminobutyric Acid (GABA). The difference of the behaviour of these transport properties for both amino-Acids was explained based on the structural differences for the monomeric zwitterionic species of AABA and GABA. Such structural differences are supported by both 1H and 13C NMR spectroscopy and theoretical calculations, which indicate that the predominant species of AABA in these solutions is the extended zwitterionic form in contrast with the curled one of GABA.
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effect of temperature on the partial molar volume isentropic compressibility and viscosity of dl 2 Aminobutyric Acid in water and in aqueous sodium chloride solutions
The Journal of Chemical Thermodynamics, 2017Co-Authors: Carmen M Romero, Ana C F Ribeiro, Diana M Rodriguez, Miguel A EstesoAbstract:Abstract Density, sound velocity and viscosity of DL-2-Aminobutyric Acid in water and in aqueous sodium chloride solutions have been measured at temperatures of (293.15, 298.15, 303.15, 308.15 and 313.15) K. The experimental results were used to determine the apparent molar volume and the apparent molar compressibility as a function of composition at these temperatures. The limiting values of both the partial molar volume and the partial molar adiabatic compressibility at infinite dilution of DL-2-Aminobutyric Acid in water and in aqueous sodium chloride solutions were determined at each temperature. The experimental viscosity values were adjusted by a least-squares method to a second order equation as proposed by Tsangaris-Martin to obtain the viscosity B coefficient which depends on the size, shape and charge of the solute molecule. The influence of the temperature on the behaviour of the selected properties is discussed in terms of both the solute hydration and the balance between hydrophobic and hydrophilic interactions between the Acids and water, and the effect of the sodium chloride concentration.
Li-rong Yang - One of the best experts on this subject based on the ideXlab platform.
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Increased productivity of L-2-Aminobutyric Acid and total turnover number of NAD+/NADH in a one-pot system through enhanced thermostability of L-threonine deaminase.
Biotechnology letters, 2018Co-Authors: Ying Wang, Guo-si Li, Pei Qiao, Mian-bin Wu, Li-rong YangAbstract:To strengthen NADH regeneration in the biosynthesis of L-2-Aminobutyric Acid (L-ABA). L-Threonine deaminase (L-TD) from Escherichia coli K12 was modified by directed evolution and rational design to improve its endurance to heat treatment. The half-life of mutant G323D/F510L/T344A at 42 °C increased from 10 to 210 min, a 20-fold increase compared to the wild-type L-TD, and the temperature at which the activity of the enzyme decreased by 50% in 15 min increased from 39 to 53 °C. The mutant together with thermostable L-leucine dehydrogenase from Bacillus sphaericus DSM730 and formate dehydrogenase from Candida boidinii constituted a one-pot system for L-ABA biosynthesis. Employing preheat treatment in the one-pot system, the biosynthesis of L-ABA and total turnover number of NAD+/NADH were 0.993 M and 16,469, in contrast to 0.635 M and 10,531 with wild-type L-TD, respectively. By using the engineered L-TD during endured preheat treatment, the one-pot system has achieved a higher productivity of L-ABA and total turnover number of coenzyme.
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increased productivity of l 2 Aminobutyric Acid and total turnover number of nad nadh in a one pot system through enhanced thermostability of l threonine deaminase
Biotechnology Letters, 2018Co-Authors: Ying Wang, Guo-si Li, Pei Qiao, Mian-bin Wu, Li-rong YangAbstract:Objective To strengthen NADH regeneration in the biosynthesis of L-2-Aminobutyric Acid (L-ABA). Results L-Threonine deaminase (L-TD) from Escherichia coli K12 was modified by directed evolution and rational design to improve its endurance to heat treatment. The half-life of mutant G323D/F510L/T344A at 42 °C increased from 10 to 210 min, a 20-fold increase compared to the wild-type L-TD, and the temperature at which the activity of the enzyme decreased by 50% in 15 min increased from 39 to 53 °C. The mutant together with thermostable L-leucine dehydrogenase from Bacillus sphaericus DSM730 and formate dehydrogenase from Candida boidinii constituted a one-pot system for L-ABA biosynthesis. Employing preheat treatment in the one-pot system, the biosynthesis of L-ABA and total turnover number of NAD+/NADH were 0.993 M and 16,469, in contrast to 0.635 M and 10,531 with wild-type L-TD, respectively. Conclusions By using the engineered L-TD during endured preheat treatment, the one-pot system has achieved a higher productivity of L-ABA and total turnover number of coenzyme.
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Increased productivity of L-2-Aminobutyric Acid and total turnover number of NAD+/NADH in a one-pot system through enhanced thermostability of L-threonine deaminase.
Biotechnology Letters, 2018Co-Authors: Ying Wang, Guo-si Li, Pei Qiao, Mian-bin Wu, Li-rong YangAbstract:Objective To strengthen NADH regeneration in the biosynthesis of L-2-Aminobutyric Acid (L-ABA). Results L-Threonine deaminase (L-TD) from Escherichia coli K12 was modified by directed evolution and rational design to improve its endurance to heat treatment. The half-life of mutant G323D/F510L/T344A at 42 °C increased from 10 to 210 min, a 20-fold increase compared to the wild-type L-TD, and the temperature at which the activity of the enzyme decreased by 50% in 15 min increased from 39 to 53 °C. The mutant together with thermostable L-leucine dehydrogenase from Bacillus sphaericus DSM730 and formate dehydrogenase from Candida boidinii constituted a one-pot system for L-ABA biosynthesis. Employing preheat treatment in the one-pot system, the biosynthesis of L-ABA and total turnover number of NAD+/NADH were 0.993 M and 16,469, in contrast to 0.635 M and 10,531 with wild-type L-TD, respectively. Conclusions By using the engineered L-TD during endured preheat treatment, the one-pot system has achieved a higher productivity of L-ABA and total turnover number of coenzyme.
Carl Henrik Gorbitz - One of the best experts on this subject based on the ideXlab platform.
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a phase transition from monoclinic c2 with z 1 to triclinic p1 with z 4 for the quasiracemate l 2 Aminobutyric Acid d methionine 1 1
Acta Crystallographica Section C-crystal Structure Communications, 2016Co-Authors: Carl Henrik Gorbitz, David S Wragg, Ingrid Marie Bergh Bakke, Christian Fleischer, Gaute Gronnevik, Maria Mykland, Yoomin Park, Kristian Wiedicke Trovik, Halvard Serigstad, Bard SundsliAbstract:Racemates of hydrophobic amino Acids with linear side chains are known to undergo a unique series of solid-state phase transitions that involve sliding of molecular bilayers upon heating or cooling. Recently, this behaviour was shown to extend also to quasiracemates of two different amino Acids with opposite handedness [Gorbitz & Karen (2015). J. Phys. Chem. B, 119, 4975–4984]. Previous investigations are here extended to an l-2-aminobutyric Acid–d-methionine (1/1) co-crystal, C4H9NO2·C5H11NO2S. The significant difference in size between the –CH2CH3 and –CH2CH2SCH3 side chains leads to extensive disorder at room temperature, which is essentially resolved after a phase transition at 229 K to an unprecedented triclinic form where all four d-methionine molecules in the asymmetric unit have different side-chain conformations and all three side-chain rotamers are used for the four partner l-2-aminobutyric Acid molecules.
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An unexpected tetragonal unit cell for N-(L-2-aminobutyryl)-L-serine.
Acta crystallographica. Section C Crystal structure communications, 2013Co-Authors: Carl Henrik Gorbitz, Vitthal N YadavAbstract:The title dipeptide {systematic name: (S)-2-[(S)-2-azaniumylbutanamido]-3-hydroxypropanoate}, C₇H₁₄N₂O₄, was synthesized in the anticipation that it would form nanoporous crystals with hexagonal symmetry. Single-crystal X-ray diffraction analysis showed that it had instead adopted a unit cell in the space group I4, similar to L-alanyl-L-alanine [Fletterick, Tsai & Hughes (1970). J. Phys. Chem. 75, 918-922]. The resulting packing arrangement has a high density for a peptide (1.462 Mg m⁻³), which is rendered possible by extensive disorder over two positions for the ethyl side chain of the 2-Aminobutyric Acid fragment and over three positions for the serine side chain.
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l 2 Aminobutyric Acid two fully ordered polymorphs with z 4
Acta Crystallographica Section B-structural Science, 2010Co-Authors: Carl Henrik GorbitzAbstract:: The crystal structure of L-2-Aminobutyric Acid, an L-alanine analogue with an ethyl rather than a methyl side chain, has proved elusive owing to problems growing diffraction quality crystals. Good diffraction data have now been obtained for two polymorphs, in space groups P2(1) and I2, revealing surprisingly complex, yet fully ordered crystalline arrangements with Z' = 4. The closely related structures are divided into hydrophilic and hydrophobic layers, the latter being the thinnest ever found for an amino Acid (other than alpha-glycine). The hydrophobic layers furthermore contain conspicuous pseudo-centers-of-symmetry, leading to overall centrosymmetric intensity statistics. Uniquely, the four molecules in the asymmetric unit can be divided into two pairs that each forms an independent hydrogen-bond network.
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L-2-Aminobutyric Acid: two fully ordered polymorphs with Z' = 4.
Acta crystallographica. Section B Structural science, 2010Co-Authors: Carl Henrik GorbitzAbstract:The crystal structure of L-2-Aminobutyric Acid, an L-alanine analogue with an ethyl rather than a methyl side chain, has proved elusive owing to problems growing diffraction quality crystals. Good diffraction data have now been obtained for two polymorphs, in space groups P2(1) and I2, revealing surprisingly complex, yet fully ordered crystalline arrangements with Z' = 4. The closely related structures are divided into hydrophilic and hydrophobic layers, the latter being the thinnest ever found for an amino Acid (other than alpha-glycine). The hydrophobic layers furthermore contain conspicuous pseudo-centers-of-symmetry, leading to overall centrosymmetric intensity statistics. Uniquely, the four molecules in the asymmetric unit can be divided into two pairs that each forms an independent hydrogen-bond network.