Interactions of montmorillonite-rich clay materials with enzymes were investigated. A 2:1 layer type raw clay mineral was purified, then ion-exchanged with Na+, K+ (Na-Mt and K-Mt), Ca2+ and Mg2+ (Ca- Mt and Mg-Mt), and further contacted with various enzyme suspensions containing α-amylase, β- amylase, cellulase, invertase, lipase, peroxidase, pectinase, urease, protease or tripsine. The acid and base properties were measured via thermal programmed desorption of NH3 and CO2, respectively. It

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... found that Ca-Mt and Mg-Mt exert stronger interactions with enzymes, generating coarser flake-shaped clay particles, as compared to Na-Mt and K-Mt. This specific behaviour is explained in terms of clay affinity towards enzymes, and correlated to the clay acid-base properties, that could have a great interest for soil chemistry. The shape and the size of clay particles were also discussed through reflection electron microscopy.