The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
David W C Macmillan - One of the best experts on this subject based on the ideXlab platform.
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photoredox α vinylation of α amino acids and n aryl Amines
Journal of the American Chemical Society, 2014Co-Authors: Adam Noble, David W C MacmillanAbstract:A new coupling protocol has been developed that allows the union of vinyl sulfones with photoredox-generated α-amino radicals to provide allylic Amines of broad diversity. Direct C–H vinylations of N-aryl tertiary Amines, as well as decarboxylative vinylations of N-Boc α-amino acids, proceed in high yield and with excellent olefin geometry control. The utility of this new allyl Amine forming reaction has been demonstrated via the syntheses of several natural products and a number of established pharmacophores.
Adam Noble - One of the best experts on this subject based on the ideXlab platform.
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photoredox α vinylation of α amino acids and n aryl Amines
Journal of the American Chemical Society, 2014Co-Authors: Adam Noble, David W C MacmillanAbstract:A new coupling protocol has been developed that allows the union of vinyl sulfones with photoredox-generated α-amino radicals to provide allylic Amines of broad diversity. Direct C–H vinylations of N-aryl tertiary Amines, as well as decarboxylative vinylations of N-Boc α-amino acids, proceed in high yield and with excellent olefin geometry control. The utility of this new allyl Amine forming reaction has been demonstrated via the syntheses of several natural products and a number of established pharmacophores.
Hallvard F. Svendsen - One of the best experts on this subject based on the ideXlab platform.
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kinetics of carbon dioxide absorption into aqueous Amine amino acid salt 3 methylamino propylAmine sarcosine solution
Chemical Engineering Science, 2011Co-Authors: Ugochukwu E. Aronu, Ardi Hartono, Hallvard F. SvendsenAbstract:Abstract A string of discs contactor apparatus was used to measure the CO 2 absorption kinetics into an unloaded aqueous Amine amino acid salt, 3-(methylamino)propylAmine/sarcosine, SARMAPA solution. The solution was prepared by mixing equinormal proportions of sarcosine, SAR and 3-(methylamino)propylAmine, MAPA. Experiments were carried out for the concentration range 1.0–5.0 kmol m −3 and for temperatures 25–62 °C. The termolecular mechanism was applied to interpret the experimental data after correcting for non-idealities from the ionic strength using an ionic correction factor. A model correlation without the ionic strength correction was found not to give a good fit to the experimental data. The reaction rate constant for aqueous SARMAPA was determined and found to be comparable to values for Amines. It increases significantly with temperature and concentration. The reaction rate constant for water is higher in the SARMAPA system than in Amine systems indicating that water contributes significantly to the overall absorption rate and more than in Amine systems. The reaction order with respect to the amino acid salt, SARMAPA, concentration varies from 1.06 to 1.43 with an average value of 1.21. A simplified approach applied to the complex speciation chemistry of the Amine amino acid salt, AAAS, system gave a good representation of the experimentally observed kinetic rate constant.
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Kinetics of carbon dioxide absorption into aqueous Amine amino acid salt: 3-(methylamino)propylAmine/sarcosine solution
Chemical Engineering Science, 2011Co-Authors: Ugochukwu E. Aronu, Ardi Hartono, Hallvard F. SvendsenAbstract:Abstract A string of discs contactor apparatus was used to measure the CO 2 absorption kinetics into an unloaded aqueous Amine amino acid salt, 3-(methylamino)propylAmine/sarcosine, SARMAPA solution. The solution was prepared by mixing equinormal proportions of sarcosine, SAR and 3-(methylamino)propylAmine, MAPA. Experiments were carried out for the concentration range 1.0–5.0 kmol m −3 and for temperatures 25–62 °C. The termolecular mechanism was applied to interpret the experimental data after correcting for non-idealities from the ionic strength using an ionic correction factor. A model correlation without the ionic strength correction was found not to give a good fit to the experimental data. The reaction rate constant for aqueous SARMAPA was determined and found to be comparable to values for Amines. It increases significantly with temperature and concentration. The reaction rate constant for water is higher in the SARMAPA system than in Amine systems indicating that water contributes significantly to the overall absorption rate and more than in Amine systems. The reaction order with respect to the amino acid salt, SARMAPA, concentration varies from 1.06 to 1.43 with an average value of 1.21. A simplified approach applied to the complex speciation chemistry of the Amine amino acid salt, AAAS, system gave a good representation of the experimentally observed kinetic rate constant.
Arminda Alves - One of the best experts on this subject based on the ideXlab platform.
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free amino acids and biogenic Amines in wines and musts from the alentejo region evolution of Amines during alcoholic fermentation and relationship with variety sub region and vintage
Journal of Food Engineering, 2004Co-Authors: Paulo Herbert, Maria Joao Cabrita, Nuno Ratola, Olga Laureano, Arminda AlvesAbstract:Abstract Characterization of musts and wines from different Alentejo sub-regions, varieties and vintages was made in terms of amino acid and Amine contents, by HPLC with fluorescence detection of OPA/FMOC derivatives. The evolution of volatile and biogenic Amines was also studied throughout 10 microvinifications. No significant increase in the levels of total volatile Amines was observed during alcoholic or spontaneous malolactic fermentation. While higher histAmine levels were only found during the storage period, an increase in the concentration of tyrAmine was confirmed in red wines immediately after malolactic fermentation, which seems to be also the main origin of putrescine. It was noticed that grape variety, region of production, and vintage can influence free amino acid and Amine contents of musts and wines, although alcoholic and malolactic fermentations can override that effect.
Matthias Höhne - One of the best experts on this subject based on the ideXlab platform.
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Bacillus anthracis ω-amino acid:pyruvate transaminase employs a different mechanism for dual substrate recognition than other Amine transaminases
Applied Microbiology and Biotechnology, 2016Co-Authors: Fabian Steffen-munsberg, Philipp Matzel, Miriam A. Sowa, Per Berglund, Uwe T. Bornscheuer, Matthias HöhneAbstract:Understanding the metabolic potential of organisms or a bacterial community based on their (meta) genome requires the reliable prediction of an enzyme’s function from its amino acid sequence. Besides a remarkable development in prediction algorithms, the substrate scope of sequences with low identity to well-characterized enzymes remains often very elusive. From a recently conducted structure function analysis study of PLP-dependent enzymes, we identified a putative transaminase from Bacillus anthracis (Ban-TA) with the crystal structure 3N5M (deposited in the protein data bank in 2011, but not yet published). The active site residues of Ban-TA differ from those in related (class III) transaminases, which thereby have prevented function predictions. By investigating 50 substrate combinations its Amine and ω-amino acid:pyruvate transaminase activity was revealed. Even though Ban-TA showed a relatively narrow Amine substrate scope within the tested substrates, it accepts 2-propylAmine, which is a prerequisite for industrial asymmetric Amine synthesis. Structural information implied that the so-called dual substrate recognition of chemically different substrates (i.e. Amines and amino acids) differs from that in formerly known enzymes. It lacks the normally conserved ‘flipping’ arginine, which enables dual substrate recognition by its side chain flexibility in other ω-amino acid:pyruvate transaminases. Molecular dynamics studies suggested that another arginine (R162) binds ω-amino acids in Ban-TA, but no side chain movements are required for Amine and amino acid binding. These results, supported by mutagenesis studies, provide functional insights for the B. anthracis enzyme, enable function predictions of related proteins, and broadened the knowledge regarding ω-amino acid and Amine converting transaminases.