PHYSICAL CHARACTERIZATION OF POROUS MATERIALS AND CORRELATION WITH THE ACTIVITY OF IMMOBILIZED ENZYME IN ORGANIC MEDIUM

A series of commonly used porous supports was characterized by determi nation of particle size distribution, porosity, surface area (total an d distributions with pore diameters) and skeletal density. The perform ance of immobilized alpha-chymotrypsin catalyzed dipeptide synthesis i n an acetonitrile medium was correlated with these physical properties . At high enzyme loading when internal mass transfer limitations are e xpected to occur, the activity can be correlated with the support char acteristic parameter. This is a combination of physical properties suc h as particle size, porosity, and volumetric porosity, which influence the substrate diffusion rate. At low enzyme loading the important par ameter is the accessible surface area, which will determine how the en zyme is distributed in the pores of the support. When assessing the ef fect of the support material on enzymatic activity, the geometric cons iderations studied here should always be contemplated before making an y assumptions about direct effects of support material on enzymatic ca talytic properties.