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Subject: search.filters.subject.540Institute: search.filters.UBSInstitut.Institut für Technische BiochemieInstitute: search.filters.UBSInstitut.Sonstige EinrichtungAuthor: search.filters.author.Bornscheuer, Uwe Theo

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Now showing 1 - 3 of 3
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    Durch Überexpression in der Hefe Pichia pastoris zu erhöhter Enantioselektivität : ein neues Kapitel in der Anwendung von Schweineleberesterase
    (2001) Musidlowska, Anna; Lange, Stefan; Bornscheuer, Uwe Theo
    Lipases and Esterases can be used as efficient biocatalysts for the preparation of a wide variety of optically pure compounds. Whereas a range of lipases - especially of microbial origin - are commercially available, only a few esterases can be obtained for the kinetic resolution of racemates or desymmetrization. In the majority of publications, pig liver esterase (PLE) is used, which is isolated from pig liver by extraction. Although it could be demonstrated, that this preparation can convert a broad range of compounds at partially very high stereoselectivity, its application is encountered with a number of disadvantages.
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    Activity of lipases and esterases towards tertiary alcohols : new insights into structure-function relationships
    (2002) Henke, Erik; Pleiss, Jürgen; Bornscheuer, Uwe Theo
    Hydrolytic enzymes are versatile biocatalysts and find increasing applications in organic synthesis and a considerable number of industrial processes using these enzymes have been commercialized. Within this class, lipases (E.C. 3.1.1.3) and carboxyl esterases (E.C. 3.1.1.1) are frequently used as they accept a broad range of non-natural substrates, are usually very stable in organic solvents and exhibit good to excellent stereoselectivity.
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    The molecular mechanism of enantiorecognition of tertiary alcohols by carboxylesterases
    (2003) Henke, Erik; Bornscheuer, Uwe Theo; Schmid, Rolf D.; Pleiss, Jürgen
    Carboxylesterases containing the sequence motif GGGX catalyze hydrolysis of esters of chiral tertiary alcohols, albeit at only low to moderate enantioselectivity towards three model substrates (linalyl acetate, methyl-1-pentin-1-yl acetate, 2-phenyl-3-butin-2-yl acetate). In order to understand the molecular mechanism of enantiorecognition and to improve enantioselectivity towards this interesting substrate class, the interaction of both enantiomers with the substrate binding sites of acetylcholinesterases and p-nitrobenzyl esterase from Bacillus subtilis was modeled and correlated to experimental enantioselectivity. For all substrate-enzyme pairs, enantiopreference and ranking by enantioselectivity could be predicted by the model. In p-nitrobenzyl esterase, one of the key residues in determining enantioselectivity was G105: exchange of this residue by alanine led to a six-fold increase of enantioselectivity (E=19) towards 2-phenyl-3-butin-2-yl acetate. However, the effect of this mutation is personalized: towards the substrate linalyl acetate, the same mutant had a reversed enantiopreference. Thus, depending on the substrate structure, the same mutant had either increased enantioselectivity or opposite enantiopreference compared to wild type enzyme.