1,721,081 research outputs found
ALFANI, F (ALFANI, F); CANTARELLA, L (CANTARELLA, L); CIRIELLI, G (CIRIELLI, G); GALLIFUOCO, A (GALLIFUOCO, A); CANTARELLA, M (CANTARELLA, M)
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Entrapping of acid phosphatase in polyhydroxyethyl methacrylate matrices. Preparation and kinetic properties
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Investigation of a process scheme for overall recovery and bioconversion of lignocellulosic biomass components
No full textMembrane reactors for the investigation of product inhibition on enzyme activity
No full textThe use of ultrafiltration cells as membranereactors is extended to the study of enzyme kinetics with productinhibition. This reactor configuration allows the lack of accuracy and instrument limitations typical of differential analysis and of time-course data analysis for experiments performed in batch reactors to be overcome. The hydrolysis of cellobiose to glucose, catalysed by β-glucosidase from Aspergillus niger (E.C. 3.2.1.4), was chosen as model system. The activity of this enzyme is suppressed by glucose according to a mixed-type inhibition pattern.
Attention was paid to the possibility of determining the presence of either reversible or irreversible productinhibition. Details of the apparatus, experimental procedure and data correlation are given. Phenomena such as thermal deactivation, mechanical stress by shear and membraneto-enzyme affinity could alter the system response and mask the effects of inhibition
Stability and activity of immobilized hydrolytic enzymes in two-liquid phase systems. Acid phosphatase, beta-glucosidase and beta-fructofuranosidase entrapped in poly (2-hydroxyethyl methacrylate) matrices
No full textEnzyme storage stability and hydrolysis yield were measured in experiments carried out with three model hydrolytic enzymes: acid phosphatase (EC 3.1.3.2), β-glucosidase (EC 3.2.1.4), and β-fructofuranosidase (EC 3.2.1.26) entrapped in hydrogels of poly(2-hydroxyethyl methacrylate). Runs were performed at 30°C, under intensive stirring (500 rev min-1), in 50% v/v biphasic media prepared with buffer and organic solvents, whose log P value varied from 0.68 to 8.8 Storage stability was also monitored in the pure solvents. The small average particle size (125–210 μm) and the intensive stirring eliminate hindrances of intra- and interphase mass transfer resistances. The hydrophilic matrix protects the enzymes against thermal and chemical deactivation, thus allowing good production per unit weight of biocatalyst. In biphasic media, storage stability, with the exception of acid phosphatase, was not dependent on solvent polarity. On the contrary, a significant trend was observed when the enzymes were stored in neat organic solvents
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