Kinetics of bonded invertase: Asymmetric polysulfone membranes

Asymmetric flat ultrafiltration membranes made from bromomethylated polysulfone were used to fix invertase chemically. The invertase reactivity of these membranes was compared with those where enzyme bonding was achieved by reacting bromomethylated polysulfone with ethylene diamine and glutaric dialdehyde which act as spacers. In both cases the invertase fixation was carried out such that its concentration at the surface facing the saccharose feed solution could be neglected. The kinetic behavior of the immobilized invertase was modelled by investigating the influence of diffusive and of convective transport across the membranes. Considering axial back-mixing of the convective flow within the membrane, the reaction can be simulated at low substrate concentrations. The heterogeneous distribution of the enzyme within the membrane matrix prevents us from calculating the kinetic data of the enzymatic reaction over the entire range of parameters.