Arylsulphatase clay interactions. II. The effect of kaolinite and montmorillonite on arylsulphatase activity

The reduction in arylsulphatase activity in the presence of kaolinite and montmorillonite was shown to be related to the total surface area of clay available for adsorption. Adsorption of arylsulphatase by kaolinite was confined to external surfaces, but with montmorillonite, interlattice sites were also involved. Evidence was presented that arylsulphatase held as a monolayer on exterior surfaces ('primary surface' adsorption), as well as that intercalated by montmorillonite, lost its activity. The remainder ('secondary surface' adsorption) retained its activity and could be removed from the clay-enzyme complex by elution.