Enzymes interaction with soil constituents

Modelling the interaction of enzymes with soil constituents... 

In addition to electrostatic forces, hydrophobic interactions are also implied in the interaction of proteins with soil constituents and this results in an interplay between different driving forces in adsorption. For example, hydrophobic interactions with clays can result from an electrostatic exchange of the hydrophilic counter-ions on the clay surface, leaving a hydrophobic siloxane surface (Staunton and Quiquam-poix, 1994). The rearrangement of the enzyme structure on the surface can be facilitated when hydrophobic amino acids come into contact with the clay hydrophobic siloxane layer and remain shielded from the water molecules of the solution. If this structural modification is accompanied by a decrease in ordered secondary structures, it will result in an additional increase in conformational entropy. This will lower the Gibbs energy of the system. The combination of all these different sub-processes gives rise to an irreversibility of the modification of conformation of enzymes on clay surfaces. 

Only a limited number of studies have been devoted to the interaction of phospho-hydrolases with soil constituents with the aim of understanding the physicochemical basis of the perturbation in the behaviour of these enzymes when they encounter the solid phase of soil. We emphasize these studies here, since they are better suited to elucidating the mechanisms by which abiotic factors influence the activity of extracellular phosphohydrolases in soil. 

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