- Using ionic liquid [EMIM][CH3COO] as an enzyme-'friendly' co-solvent for resolution of amino acids
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An ionic liquid (IL), 1-ethyl-3-methylimidazolium acetate [EMIM][CH3COO], was used in 0-4.0 M (~60% IL, v/v), as a nonvolatile organic medium for the enzymatic resolution of amino acids. When dl-phenylalanine methyl ester was studied as a model substrate, high enantiomeric excesses (ee) of l-amino acid were obtained in all ionic concentrations; however, lower yields were observed at high IL concentrations. This IL is more enzyme-'friendly' than the hydrophilic organic solvent acetonitrile and those ILs containing chaotropic anions (such as [EMIM][OTs]). Among three proteases and two lipases investigated, lyophilized Bacillus licheniformis protease exhibited the best enantioselectivity and activity. Highly enantioselective resolutions were also produced for several other amino acids in 2.0 M IL. Interestingly, high ee were also found in deuterium oxide (D2O) rather than in ordinary water, and a further enhancement was achieved with the co-existence of [EMIM][CH3COO]. The heavy water effect was explained in terms of protein stabilization by D2O. The secondary structural changes of enzyme in various media were interpreted by the second derivatives of FT-IR spectra.
- Zhao, Hua,Jackson, Lee,Song, Zhiyan,Olubajo, Olarongbe
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p. 2491 - 2498
(2007/10/03)
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- Synthesis and antitumor activity of platinum(II) complexes containing substituted ethylenediamine ligands
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The synthesis of substituted ethylenediamines, their reactions with K2PtCl4 to give the dichloroplatinum(II) complexes, and the exchange of the chloro ligands for other leaving groups are described.The new compounds have been tested as antitumor agents both in vitro using the hormone independent human mammary carcinoma cell line MDA-MB 231 as well as in vivo using the lymphocytic P388 leukemia of the CD2F1-mouse.In the P388 test, 53 of the 55 tested complexes fulfill the minimum activity of 125percent T/C required for a substance to be active.
- Brunner, Henri,Hankofer, Peter,Holzinger, Ulrich,Treittinger, Barbara,Schoenenberger, Helmut
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