A stepwise approach to the understanding of extracellular enzyme activity in soil. II. Competitive effects on the adsorption of a beta-D-glucosidase in mixed mineral or organo-mineral systems.
A previous study has shown the effect of individual mineral surfaces on the activity of sweet almond beta-D-glucosidase. We now consider more complex situations likely to occur in soil, such as adsorption onto mixtures of different mineral surfaces, and the effect on enzyme activity of mineral surfaces with organic coatings. The effect of the order of addition of the minerals to enzyme suggests that the rate of adsorption is limited by the diffusion of the protein towards the interface and is not influenced by the magnitude of attractive forces between the protein and the surface. Adsorption is found to be quasi-irreversible. A study of the effect of artificial coatings of montmorillonite on enzyme activity led to the conclusion that an exchange of the enzyme with molecules of the coating occurs. This exchange is dependent upon the adsorption energy of the molecules of the coating and the electric charge of beta-D-glucosidase. This model is used for the interpretation of the effect of natural clay-humic complexes on enzyme activity.
D000327:Adsorption; D000538:Aluminum Silicates / Q000032:analysis; D001546:Bentonite; D000077215:Clay; D005959:Glucosidases / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D008903:Minerals / Q000032:analysis*; D009113:Muramidase / Q000032:analysis; D011092:Polyethylene Glycols / Q000032:analysis; D012987:Soil / Q000032:analysis*; D001617:beta-Glucosidase / Q000302:isolation & purification*
D000538:Aluminum Silicates; D008903:Minerals; D012987:Soil; D001546:Bentonite; D011092:Polyethylene Glycols; D005959:Glucosidases; D009113:Muramidase; D001617:beta-Glucosidase; D000077215:Clay