title: Use of a diffusion model for mono- and bicomponent anion-exchange of two isoenzymes of glucoamylase from Aspergillus niger in a fixed bed.
abstract: The adsorption of glucoamylases I and II (GA I and GA II, respectively) from Aspergillus niger on the anion exchanger DEAE-Toyopearl 650 was studied in fixed-bed experiments, and the effect of temperature, flowrate, inlet concentration, bed length, and particle size on the process was characterized. The anion exchanger showed a higher adsorption capacity for the more active isoenzyme GA I in all experimental conditions studied. A mathematical model accounting for external and pore diffusion and nonlinear equilibrium isotherm (for GA I) was used to fit the experimental breakthrough curves, showing very accurate fittings in all of the operating conditions. The values of the pore diffusion coefficient at 15, 20, and 25 degrees C were, respectively, 1.25 x 10(-)(11), 1.46 x 10(-)(11) and 1.83 x 10(-)(11) (for GA I) and 1.82 x 10(-)(11), 2.44 x 10(-)(11) and 2.73 x 10(-)(11) (for GA II) m(2)/s. Bicomponent adsorption experiments showed no significant interference effects between GA I and GA II, and so the mathematical model was again used to fit these experiments, yielding very satisfactory results.
authors.affiliation: Department of Chemical Engineering, Faculty of Chemistry, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Soriano
authors.forename: L Fernando
authors.initials: LF
authors.lastname: Bautista
authors.forename: Mercedes
authors.initials: M
authors.lastname: Martínez
authors.forename: José
authors.initials: J
authors.lastname: Aracil
mesh_terms: D000327:Adsorption; D000838:Anions; D001234:Aspergillus niger / Q000201:enzymology*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D003198:Computer Simulation; D004058:Diffusion; D004789:Enzyme Activation; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry* / Q000302:isolation & purification*; D007527:Isoenzymes / Q000032:analysis / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D016062:Porosity; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D000838:Anions; D007527:Isoenzymes; D005087:Glucan 1,4-alpha-Glucosidase