Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 327449
Title Substrate sorption into the polymer matrix of Novozym 435 and its effect on the enantiomeric ratio determination
Author(s) Heinsman, N.W.J.T.; Schroën, C.G.P.H.; Padt, A. van der; Franssen, M.C.R.; Boom, R.M.; Riet, K. van 't
Source Tetrahedron: Asymmetry 14 (2003). - ISSN 0957-4166 - p. 2699 - 2704.
Department(s) Food Process Engineering
Laboratory for Organic Chemistry
Sub-department of Food and Bioprocess Engineering
Publication type Refereed Article in a scientific journal
Publication year 2003
Keyword(s) candida-rugosa lipase - enantioselective esterification - 2-methylalkanoic acids - 4-methyloctanoic acid - quantitative-analyses - water activity - resolution - polyethylene - absorption - hydrogels
Abstract In the enantioselective esterification of 4-methyloctanoic acid with ethanol by immobilised Candida antarctica lipase B (Novozym 435®), the enantiomeric excesses determined during the course of the reaction deviated strongly from the theoretical values, leading to unacceptably large confidence intervals for the enantiomeric ratio (E value). This observation was in contrast to our previous findings for transesterification and hydrolysis reactions with this enzyme. Herein, the three reactions are compared; the anomalous results in the esterification reaction appear to be caused by adsorption of 4-methyloctanoic acid inside the enzyme beads. We found that on average 1.19 g of 4-methyloctanoic acid was incorporated per g of Novozym 435®. If the concentration of this substrate was adjusted accordingly in the calculations, the resulting E values showed acceptable confidence intervals. In previous research on transesterification reactions in excess apolar solvent (comparable affinity for the beads), sorption does not play an important role because only small amounts of substrate were lost. For hydrolysis reactions, sorption takes place but the acid is released from the beads upon titration and no effect on the E value is found. However, for esterification reactions, sorption should not be neglected since there is no driving force to release the acid from the beads.
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