Immobilization of enzymes in porous solids under restricted diffusion conditions

Abstract

A restricted diffusion model is developed to study the immobilization of enzyme in porous solid supports. Simulation studies have been carried out for various combinations of process variables and parameters of the immobilization system. The model has also been used to develop Md. M. Hossain and D. D. Do Department of Chemical EngineeringUniversity of Queensland St. Lucia. Qld. 4067, Australia a method for estimating the intrinsic rate constant of immobilization when enzyme diffusion into the support is restricted. Results of experiments in which glucose oxidase was immobilized in porous glass supports are consistent with model simulations.

Effects of Solute Adsorption on Hindered Diffusion Uptake Rates in Finite Bath Experiments

“…A similar assumption has been made by Hossain et al (1986) in modeling enzyme immobilization. In equation (22), Am represents the pore cross-sectional area with an adsorbed monolayer of solute molecules qm' For a monolayer of spherical molecules of diameter D m in a pore of diameter D po , we have…”

“…the adsorbed molecules may indirectly effect the intrapore diffusivity by modifying the catalyst pore structure. Along these lines, Hossain et al (1986) studied the immobilization of enzymes in porous materials and developed a model incorporating constriction of pore mouths due to the adsorbed layer of immobilized enzymes. A better understanding of adsorptive hindered diffusion behaviour in catalyst pores will aid in designing better catalysts for the treatment of macromolecular feedstocks, such as occurs in the hydrotreatment of petroleum resids and coal-derived liquids.…”

Three‐Enzyme Phosphorylase Cascade Immobilized on Solid Support for Biocatalytic Synthesis of Cello−oligosaccharides

“…However, for Z− Bl ScP and even more so for Z− Cu CbP, the catalytic effectiveness of the immobilized enzymes decreased dependent on the enzyme loading (Figure A,B). As all the activity assays employed substrates in large excess at fully saturating concentrations, the effect was unlikely to arise from limitations in substrate available to the immobilized enzyme in consequence of physical processes such as pore diffusion and partitioning . A plausible reason for the observed loss of activity at high enzyme loading is that enzyme clustering occurs at suitable nucleation sites on the solid surface .…”

Configurational diffusion of asphaltenes in fresh and aged catalyst extrudates. Final technical report, September 20, 1991--September 30, 1996

“…A similar assumption has been made by Hossain et al (1986) The parameter E, reflects the ratio of equilibrium adsorption capacity to monolayer adsorption capacity, evaluated at the initial bath concentration.…”

“…When adsorption of solute molecules occurs during a hindered diffusion process, as in heterogeneous catalysis, the adsorbed molecules may indirectly affect the intrapore diffusivity by modifying the catalyst pore structure. Along these lines, Hossain et al (1986) studied the immobilization of enzymes in porous materials and developed a model incorporating constriction of pore mouths due to the adsorbed layer of immobilized enzymes. A better understanding of adsorptive hindered diffusion behavior in catalyst pores will aid 118 in designing better catalysts for the treatment of macromolecular feedstocks, such as occurs in the hydrotreatment of petroleum resids and coal-derived liquids.…”