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Charles A Schmuttenmaer - One of the best experts on this subject based on the ideXlab platform.
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terahertz spectroscopy and density functional theory calculations of dl Norleucine and dl methionine
Journal of Physical Chemistry A, 2018Co-Authors: Jens Neu, Heinrich Nikonow, Charles A SchmuttenmaerAbstract:We present terahertz (THz) measurements and density functional theory (DFT) calculations of two amino acid crystals: dl-Norleucine and dl-methionine. Their molecular structures are very similar and therefore also their crystal structures. We report the absorption spectra for both amino acids, which have a strong resonance at 1.87 THz in dl-Norleucine and 1.94 THz in dl-methionine. In addition, we find a higher frequency resonance at 2.49 THz in dl-methionine, which has no corresponding mode in dl-Norleucine. The experimental data are supported by DFT calculations, which show that the origin of the two strongest vibrational modes in dl-Norleucine and dl-methionine are based on the same underlying vibrational motions, whereas the 2.49 THz resonance in dl-methionine is due to the motion of the sulfur atom, which is not present in dl-Norleucine.
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Terahertz Spectroscopy and Density Functional Theory Calculations of dl-Norleucine and dl-Methionine
2018Co-Authors: Jens Neu, Heinrich Nikonow, Charles A SchmuttenmaerAbstract:We present terahertz (THz) measurements and density functional theory (DFT) calculations of two amino acid crystals: dl-Norleucine and dl-methionine. Their molecular structures are very similar and therefore also their crystal structures. We report the absorption spectra for both amino acids, which have a strong resonance at 1.87 THz in dl-Norleucine and 1.94 THz in dl-methionine. In addition, we find a higher frequency resonance at 2.49 THz in dl-methionine, which has no corresponding mode in dl-Norleucine. The experimental data are supported by DFT calculations, which show that the origin of the two strongest vibrational modes in dl-Norleucine and dl-methionine are based on the same underlying vibrational motions, whereas the 2.49 THz resonance in dl-methionine is due to the motion of the sulfur atom, which is not present in dl-Norleucine
V. G. Badelin - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic characteristics of acid base reactions in aqueous solutions of dl α alanyl dl Norleucine
Russian Journal of Physical Chemistry A, 2018Co-Authors: A I Lytkin, O. N. Krutova, V. G. Badelin, V V Chernikov, V P BarannikovAbstract:The heat effects of the interaction between a solution of DL-α-alanyl-DL-Norleucine and solutions of HNO3 at different pH values at 288.15 and 308.15 K and ionic strength values of 0.5, 1.0, and 1.5 (background electrolyte, KNO3) are measured via calorimetry. The heat effects of the stepwise dissociation of the dipeptide are determined. Standard thermodynamic characteristics (ΔrH°, ΔrG°, ΔrS°, and $$\Delta C_{p}^{^\circ }$$ ) of the reactions of acid–base interaction in aqueous solutions of DL-α-alanyl-DL-Norleucine are calculated. The relation between the thermodynamic characteristics of the dissociation of a dipeptide with the structure of this compound is considered.
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Thermochemistry of the dissolution of DL-α-alanyl-DL-Norleucine in aqueous solutions of amides at 298.15 K
Russian Journal of Physical Chemistry A, 2013Co-Authors: V. I. Smirnov, V. G. BadelinAbstract:Enthalpies of the dissolution of DL-α-alanyl-DL-Norleucine are determined by calorimetry in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA) at a concentration of amides of x _2 = 0–0.4 molar parts and T = 298.15 K. Standard values of enthalpies of dissolution Δ_sol H ^o and Δ_tr H ^o of DL-α-alanyl-DL-Norleucine transfer from water to binary solvent are calculated, along with the enthalpy coefficients of pair interactions h _ xy of DL-α-alanyl-DL-Norleucine with amide molecules. The effect of the composition of water-organic mixtures and the structure of amides on the enthalpy characteristics of dissolution and transition of DL-α-alanyl-DL-Norleucine is considered. Quantitative estimates of the contributions to energy from DL-α-alanyl-DL-Norleucine-amides pair interactions determined by the polarity, polarizability, and electron acceptor and electron donor ability of organic cosolvents are given using the Kamlet-Taft correlation equation.
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influence of the composition of aqueous alcohol solvents on thermodynamic characteristics of dl α alanyl dl Norleucine dissolution at 298 15k
Thermochimica Acta, 2012Co-Authors: Valeriy I Smirnov, V. G. BadelinAbstract:Abstract Dissolution enthalpies (ΔsolHm) of dl -α-alanyl- dl -Norleucine in binary mixtures containing water + (EtOH, 1-PrOH and 2-PrOH at 0–0.4 mole fraction) at 298.15 K and atmospheric pressure have been determined as a function of the composition using an isothermic calorimeter. The results obtained have been used to calculate standard enthalpies of a solution (ΔsolH°) and transfer (ΔtrH) of dl -α-alanyl- dl -Norleucine from water into the mixtures as well as enthalpy coefficients of pairwise interaction (hxy) of the solute with alcohols in aqueous media. The ΔtrH° values are positive for all mixtures over the whole composition range. The influence of the co-solvent structure and of the content of mixtures and of a side-chain of peptide on the change of ΔtrH° (hxy) is discussed.
Hidemoto Kurokawa - One of the best experts on this subject based on the ideXlab platform.
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optical resolution by replacing crystallization of ammonium salts of n acetyl dl 2 aminobutanoic acid n acetyl dl norvaline and n acetyl dl Norleucine
Bulletin of the Chemical Society of Japan, 1991Co-Authors: Tadashi Shiraiwa, Masahiro Yamauchi, Takatoshi Yamauchi, Takao Yamane, Makoto Nagata, Hidemoto KurokawaAbstract:Ammonium salts of N-acetyl-DL-2-aminobutanoic acid, N-acetyl-DL-norvaline (DL-AcNva·AM salt), and N-acetyl-DL-Norleucine were optically resolved by replacing crystallization in the presence of the ammonium salt of N-acetyl-L-alanine to give their salts with L-configuration. The optical resolution of the DL-AcNva·AM salt, espcially, gave the optically pure L-AcNva4·AM salt by purification in 80% yield based on the half amount of the DL-salt used as the starting material.
Uwe Horn - One of the best experts on this subject based on the ideXlab platform.
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trace element associated reduction of Norleucine and norvaline accumulation during oxygen limitation in a recombinant escherichia coli fermentation
Microbial Cell Factories, 2013Co-Authors: Michael Biermann, Julia Linnemann, Uwe Knupfer, Sebastian Vollstadt, Bettina Bardl, Guido Seidel, Uwe HornAbstract:Background Norleucine and norvaline belong to a group of non-canonical amino acids which are synthesized as byproducts in the branched chain amino acid metabolism of Escherichia coli. The earlier observed misincorporation of these rare amino acids into recombinant proteins has attracted increasing attention due to the rising use of protein based biopharmaceuticals in clinical application. Experimental data revealed pyruvate overflow inducing conditions, which typically occur in oxygen limited zones of large-scale fermentations as a major reason leading to norvaline and Norleucine synthesis during E. coli cultivation. Previous approaches to suppress misincorporation of Norleucine and norvaline considered growth media supplementation with the relevant canonical isostructural compounds, but no research was performed on the impact of the overflow metabolism related trace elements molybdenum, nickel and selenium. These elements form essential parts of the formate hydrogen lyase (FHL) metalloprotein complex, which is a key enzyme of anaerobic pyruvate metabolism in E. coli and could therefore represent a crucial connection to the pyruvate accumulation associated biosynthesis of rare amino acids.
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Simultaneous analysis of the non-canonical amino acids Norleucine and norvaline in biopharmaceutical-related fermentation processes by a new ultra-high performance liquid chromatography approach
Amino Acids, 2013Co-Authors: Michael Biermann, Julia Linnemann, Uwe Knupfer, Sebastian Vollstadt, Bettina Bardl, Guido Seidel, Uwe HornAbstract:In this study, a precise and reliable ultra-high performance liquid chromatography (UHPLC) method for the simultaneous determination of non-canonical (norvaline and Norleucine) and standard amino acids (aspartic acid, glutamic acid, serine, histidine, glycine, threonine, arginine, tyrosine, methionine, valine, phenylalanine, isoleucine, leucine) in biopharmaceutical-related fermentation processes was established. After pre-column derivatization with ortho -phthaldialdehyde and 2-mercaptoethanol, the derivatives were separated on a sub -2 μm particle C_18 reverse-phase column. Identification and quantification of amino acids were carried out by fluorescence detection. To test method feasibility on standard HPLC instruments, the assay was properly transferred to a core–shell particle C_18 reverse-phase column. The limits of detection showed excellent sensitivity by values from 0.06 to 0.17 pmol per injection and limits of quantification between 0.19 and 0.89 pmol. In the present study, the newly established UHPLC method was applied to a recombinant antibody Escherichia coli fermentation process for the analysis of total free amino acids. We were able to specifically detect and quantify the unfavorable amino acids in such complex samples. Since we observed trace amounts of norvaline and Norleucine during all fermentation phases, an obligatory process monitoring should be considered to improve quality of recombinant protein drugs in future.
Jens Neu - One of the best experts on this subject based on the ideXlab platform.
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terahertz spectroscopy and density functional theory calculations of dl Norleucine and dl methionine
Journal of Physical Chemistry A, 2018Co-Authors: Jens Neu, Heinrich Nikonow, Charles A SchmuttenmaerAbstract:We present terahertz (THz) measurements and density functional theory (DFT) calculations of two amino acid crystals: dl-Norleucine and dl-methionine. Their molecular structures are very similar and therefore also their crystal structures. We report the absorption spectra for both amino acids, which have a strong resonance at 1.87 THz in dl-Norleucine and 1.94 THz in dl-methionine. In addition, we find a higher frequency resonance at 2.49 THz in dl-methionine, which has no corresponding mode in dl-Norleucine. The experimental data are supported by DFT calculations, which show that the origin of the two strongest vibrational modes in dl-Norleucine and dl-methionine are based on the same underlying vibrational motions, whereas the 2.49 THz resonance in dl-methionine is due to the motion of the sulfur atom, which is not present in dl-Norleucine.
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Terahertz Spectroscopy and Density Functional Theory Calculations of dl-Norleucine and dl-Methionine
2018Co-Authors: Jens Neu, Heinrich Nikonow, Charles A SchmuttenmaerAbstract:We present terahertz (THz) measurements and density functional theory (DFT) calculations of two amino acid crystals: dl-Norleucine and dl-methionine. Their molecular structures are very similar and therefore also their crystal structures. We report the absorption spectra for both amino acids, which have a strong resonance at 1.87 THz in dl-Norleucine and 1.94 THz in dl-methionine. In addition, we find a higher frequency resonance at 2.49 THz in dl-methionine, which has no corresponding mode in dl-Norleucine. The experimental data are supported by DFT calculations, which show that the origin of the two strongest vibrational modes in dl-Norleucine and dl-methionine are based on the same underlying vibrational motions, whereas the 2.49 THz resonance in dl-methionine is due to the motion of the sulfur atom, which is not present in dl-Norleucine
