BioSoft-Colloquium: "Adsorption, Diffusion and Catalytic Activity of Enzymes in Nanoporous Materials"
Prof. M.-O. Coppens, Department of Chemical Engineering, University College London
- 22 Apr 2013 16:00
Studies of transport and adsorption of enzymes in porous materials are of interest to bio-separations, sensing and a variety of biotechnological and biomedical applications. In addition, immobilising costly enzymes on the internal surface of high-surface area nanoporous materials allows their reutilisation in bio-catalytic processes.
By using monodisperse particles of mesoporous silica SBA-15 (fig.1), containing a parallel array of pores with a unique diameter that is tunable within a range of, at least, 5-12 nm, we have studied how nano-confinement inside these narrow pores affects diffusion, adsorption and catalysis. These studies were carried out for lysozyme and myoglobin.
The results from experiments of diffusion of enzymes in SBA-15 are favourably compared to theoretical predictions, and show that both electrostatics and steric confinement effects play an important role. External surface barriers may be significant. A simple geometrical model predicts the adsorption isotherms at the isoelectric point. Remarkably, the catalytic activity of the enzymes for test reactions is increased multiple-fold over that of the free enzymes in solution, especially in the narrowest, most tightly confining pores. Insights behind the increased stability of enzymes are obtained from FTIR spectroscopy, calorimetry, and ongoing neutron scattering experiments and molecular simulations.