Adsorption, desorption, and activity of glucose oxidase on selected clay species

Publisher Website
Google Scholar
Abstract
The adsorption of the enzyme glucose oxidase (EC 1.1.3.4) to clays followed the pattern described for other proteins as being pH dependent. Maximum adsorption occurred at or below the isoelectric point of the enzyme. The amount of enzyme adsorbed to clay was influenced by the type of clay used and the saturating cations. Initially adsorbed enzyme showed low specific activities, and as amounts of enzyme adsorbed approached maximum saturation of clay, specific activities increased approaching that determined for free enzyme. The adsorption of glucose oxidase involved a temperature-independent cation-exchange mechanism, and enzyme adsorbed to surfaces of clay could be desorbed in active form by elevation of pH of suspending solution. This was followed by a slower temperature-dependent fixation, probably by H bonding, which resulted in protein being irreversibly adsorbed to clay surfaces. It is proposed that an adsorption of glucose oxidase to clay surfaces unraveling of the protein structure occurred, which allowed penetration of protein into the interlamellar spaces of montmorillonite. This proposal as based on the observed expansion of montmorillonite to 23A, and the decrease in amount of a 2nd-protein lysozyme adsorbed with extended incubation times of glucose oxidase -clay complexes at pH 4.5.

This publication has 3 references indexed in Scilit: