title: Racemization of undesired enantiomers: Immobilization of mandelate racemase and application in a fixed bed reactor.
abstract: Production of optically pure products can be based on simple unselective synthesis of racemic mixtures combined with a subsequent separation of the enantiomers; however, this approach suffers from a 50% yield limitation which can be overcome by racemization of the undesired enantiomer and recycling. Application of biocatalyst for the racemization steps offers an attractive option for high-yield manufacturing of commercially valuable compounds. Our work focuses on exploiting the potential of racemization with immobilized mandelate racemase. Immobilization of crude mandelate racemase via covalent attachment was optimized for two supports: Eupergit(®) CM and CNBr-activated Sepharose 4 Fast Flow. To allow coupling of enzymatic reaction with enantioselective chromatography, a mobile phase composition compatible with both processes was used in enzymatic reactor. Kinetic parameters obtained analyzing experiments carried out in a batch reactor could be successfully used to predict fixed-bed reactor performance. The applicability of the immobilized enzyme and the determined kinetic parameters were validated in transient experiments recording responses to pulse injections of R-mandelic acid. The approach investigated can be used for futher design and optimization of high yield combined resolution processes. The characterized fixed-bed enzymatic reactor can be integrated e.g. with chromatographic single- or multicolumn steps in various configurations.
authors.affiliation: Max-Planck Institute for Dynamics of Complex Technical System, Physical and Chemical Foundations of Process Engineering, Magdeburg, Germany.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Wrzosek
authors.affiliation: Max-Planck Institute for Dynamics of Complex Technical System, Physical and Chemical Foundations of Process Engineering, Magdeburg, Germany.|Swiss Federal Institute of Technology in Lausanne EPFL, Section of Chemistry and Chemical Engineering, Lausanne, Switzerland.
authors.forename: Mariel A García
authors.initials: MA
authors.lastname: Rivera
authors.affiliation: Max-Planck Institute for Dynamics of Complex Technical System, Analysis and Redesign of Biological Networks, Magdeburg, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Bettenbrock
authors.affiliation: Max-Planck Institute for Dynamics of Complex Technical System, Physical and Chemical Foundations of Process Engineering, Magdeburg, Germany. seidel-morgenstern@mpi-magdeburg.mpg.de.|Otto von Guericke University, Chemical Process Engineering, Magdeburg, Germany. seidel-morgenstern@mpi-magdeburg.mpg.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Seidel-Morgenstern
mesh_terms: D061249:Batch Cell Culture Techniques; D055162:Biocatalysis; D019149:Bioreactors; D004800:Enzymes, Immobilized / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development*; D007700:Kinetics; D008333:Mandelic Acids / Q000737:chemistry; D019998:Racemases and Epimerases / Q000235:genetics / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D004800:Enzymes, Immobilized; D008333:Mandelic Acids; D019998:Racemases and Epimerases; C021540:mandelate racemase; C037938:mandelic acid
keywords: Enzyme immobilization; Fixed-bed reactor; Mandelate racemase; Racemization; Reversible Michealis-Menten kinetics