Membrane reactors for the investigation of product inhibition on enzyme activity

The 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.