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Research Interests: Chemistry, British, Membrane Proteins, Medicine, Molecular Mechanics, and 15 moreMutation, Animals, Stereochemistry, Radioligand Assay, Tritium, Receptor, Amino Acid Sequence, Amino Acid Substitution Rates, Catecholamines, Ligands, Molecular Structure, binding sites, CHO cells, Cricetinae, and Pharmacology and pharmaceutical sciences
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ABSTRACT Racemic α-tryptophan was chemoselectively transformed into the enantiomers of β-tryptophan ethyl ester. The key step in achieving enantiopurity was the N-acylation of the 3-amino-4-(3-indolyl)butanenitrile intermediate with... more
ABSTRACT Racemic α-tryptophan was chemoselectively transformed into the enantiomers of β-tryptophan ethyl ester. The key step in achieving enantiopurity was the N-acylation of the 3-amino-4-(3-indolyl)butanenitrile intermediate with Candida antarctica lipase A (CAL-A). The enzymatic N-acylation of racemic β-tryptophan ethyl ester was also studied. CAL-A was highly (R)-enantioselective in the present kinetic resolutions, leading to a mixture of the butanamide product with an (R)-configuration and the unreacted starting material with an (S)-configuration at 50% conversion.
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Racemic ethyl 3-hydroxybutanoate rac-1 was transformed into ethyl (R)-acetoxybutanoate (ee=92%) with 85–90% chemical yields using enantioselective acylation with isopropenyl acetate in the presence of Candida antarctica lipase B (CAL-B,... more
Racemic ethyl 3-hydroxybutanoate rac-1 was transformed into ethyl (R)-acetoxybutanoate (ee=92%) with 85–90% chemical yields using enantioselective acylation with isopropenyl acetate in the presence of Candida antarctica lipase B (CAL-B, Novozym 435) under solvent-free conditions, followed by mesylation of the unreacted (S)-alcohol in the reaction mixture and inversion of configuration with cesium acetate in DMF in one pot. When the (R)-acetoxybutanoate
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ABSTRACT We present a mechanism for agonist-promoted alpha(2A)-adrenergic receptor (alpha(2A)-AR) activation based on structural, pharmacological, and theoretical evidence of the interactions between phenethylamine ligands and... more
ABSTRACT We present a mechanism for agonist-promoted alpha(2A)-adrenergic receptor (alpha(2A)-AR) activation based on structural, pharmacological, and theoretical evidence of the interactions between phenethylamine ligands and alpha(2A)-AR. In this study, we have: 1) isolated enantiomerically pure phenethylamines that differ both in their chirality about the beta-carbon, and in the presence/absence of one or more hydroxyl groups: the beta-OH and the catecholic meta- and para-OH groups; 2) used [(3)H]UK-14,304 [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine; agonist] and [(3)H]RX821002 [2-(2-methoxy-1,4-benzodioxan-2-yl)-2-imidazoline; antagonist] competition binding assays to determine binding affinities of these ligands to the high- and low-affinity forms of alpha(2A)-AR; 3) tested the ability of the ligands to promote receptor activation by measuring agonist-induced stimulation of [(35)S]GTPgammaS binding in isolated cell membranes; and 4) used automated docking methods and our alpha(2A)-AR model to predict the binding modes of the ligands inside the alpha(2A)-AR binding site. The ligand molecules are sequentially missing different functional groups, and we have correlated the structural features of the ligands and ligand-receptor interactions with experimental ligand binding and receptor activation data. Based on the analysis, we show that structural rearrangements in transmembrane helix (TM) 5 could take place upon binding and subsequent activation of alpha(2A)-AR by phenethylamine agonists. We suggest that the following residues are important in phenethylamine interactions with alpha(2A)-AR: Asp113 (D(3.32)), Val114 (V(3.33)), and Thr118 (T(3.37)) in TM3; Ser200 (S(5.42)), Cys201 (C(5.43)), and Ser204 (S(5.46)) in TM5; Phe391 (F(6.52)) and Tyr394 (Y(6.55)) in TM6; and Phe411 (F(7.38)) and Phe412 (F(7.39)) in TM7.
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Abstract The immobilized enzyme lipase acts as an efficient, selective and durable catalyst in the direct transformation of unsaturated carboxylic acids to epoxides, which are used as chemical intermediates and bio-lubricants.... more
Abstract The immobilized enzyme lipase acts as an efficient, selective and durable catalyst in the direct transformation of unsaturated carboxylic acids to epoxides, which are used as chemical intermediates and bio-lubricants. Experimental data obtained from the epoxidation of a model molecule, oleic acid in a laboratory-scale isothermal batch reactor were critically evaluated and mathematically modelled in the most precise way. Several rival surface reaction mechanisms were proposed and rate equations based on these mechanisms were derived. The rate equations were implemented in a multiphase model for the laboratory-scale batch reactor and the kinetic and adsorption parameters included in the rate equations were estimated with non-linear regression analysis. Based on the parameter estimation statistics and chemical knowledge, the most plausible kinetic models for the chemo-enzymatic epoxidation of oleic acid on the immobilized lipase catalyst were selected. The best kinetic models gave a good reproduction of the experimental data. The models can be used to predict the performance of enzymatic epoxidation of unsaturated fatty acids.
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As a definition, enzyme catalysis in an organic solvent means enzymatic reactions in a medium which contains only few per cent (1–2%) of water or in an anhydrous organic solvent (1). Dry enzyme powder is insoluble in such a system, and... more
As a definition, enzyme catalysis in an organic solvent means enzymatic reactions in a medium which contains only few per cent (1–2%) of water or in an anhydrous organic solvent (1). Dry enzyme powder is insoluble in such a system, and consequently the biotransformation proceeds by heterogeneous catalysis. Polyethylene glycol (PEG)-modified enzymes are able to dissolve in organic solvents, making homogeneous catalysis feasible as well (2, 3).
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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The work describes fluorine-activated and N-Boc-activated β-lactams as acyl donors to N-nucleophiles in the presence of Burkholderia cepacia lipase (lipase PS-D). Fluorine activation at the β-lactam ring causes the ring to open in high... more
The work describes fluorine-activated and N-Boc-activated β-lactams as acyl donors to N-nucleophiles in the presence of Burkholderia cepacia lipase (lipase PS-D). Fluorine activation at the β-lactam ring causes the ring to open in high enantioselectivity and allows the preparation of β-dipeptides and β-amino amides. In the case of N-Boc-activation, the chemical ring opening is significant. β-Dipeptide formation can then be considerably enhanced by the presence of lipase PS-D and/or by temperature.
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... Colloids and Surfaces B: Biointerfaces 4 (1995) 121127 Selective enzymatic reactions using microemulsionbased gels Sune Backlund a Folke Eriksson a Liisa T. Kanerva b Maria Rantala a,, a ... [36] S. Backlund, F. Eriksson, LT Kanerva,... more
... Colloids and Surfaces B: Biointerfaces 4 (1995) 121127 Selective enzymatic reactions using microemulsionbased gels Sune Backlund a Folke Eriksson a Liisa T. Kanerva b Maria Rantala a,, a ... [36] S. Backlund, F. Eriksson, LT Kanerva, S. Karlsson, G. Lundsten, M. Rantala, E ...
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Almond meal and Sorghum bicolor shoots were used as the sources of oxynitrilases for the preparation of a number (R)- and (S)-arylcyanohydrins, respectively, from the corresponding aldehydes in diisopropyl ether. Two different in situ... more
Almond meal and Sorghum bicolor shoots were used as the sources of oxynitrilases for the preparation of a number (R)- and (S)-arylcyanohydrins, respectively, from the corresponding aldehydes in diisopropyl ether. Two different in situ methods were used to introduce hydrogen cyanide into the reaction mixture. In method 1, acetone cyanohydrin decomposes enzymatically and/or chemically to hydrogen cyanide. In method 2,
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A chemo-enzymatic method for the preparation of homochiral esters of 14 secondary alcohols with 100% theoretical yields is described in one pot through two steps: the lipase-catalysed kinetic resolution followed by the Mitsunobu... more
A chemo-enzymatic method for the preparation of homochiral esters of 14 secondary alcohols with 100% theoretical yields is described in one pot through two steps: the lipase-catalysed kinetic resolution followed by the Mitsunobu esterification of the free alcohol enantiomer in situ in the resolution mixture. Mathematical equations which link the enzymatic and chemical steps were derived, resulting in an enantioconvergent