Conformational changes of enzymes adsorbed at liquid- solid interface: Relevance to enzymatic activity

International audienceFTIR-ATR spectroscopy has been used to study in-situ adsorption of enzymes at water/solid interfaces so as to better understand how conformational changes may monitor enzymatic activity. As the adsorption process depends on hydrophobic and electrostatic interactions, conformational changes have been studied as a function of the nature of the adsorbing substrates: hydrophobic or hydrophilic character. Adsorption kinetics of two examples of serine enzyme, -chymotrypsin (-chym) and Humicola lanuginosa lipase (HLL), have been studied. Both secondary structure and solvation of the adsorbed enzymes have been compared to the dissolved enzymes. While the positively charged -chym was adsorbed on a negatively charged hydrophilic support with minor structural changes, the negatively charged lipase has no affinity for a similar support. Both enzymes were strongly retained on the hydrophobic support. The secondary and tertiary structures of the -chym adsorbed on hydrophobic support were strongly altered, in correlation with the inhibition of enzymatic hydrolysis. The specific solvation obtained for the adsorbed HLL is consistent with the existence of the open conformer, in relation with the enhanced enzymatic activity at the water/hydrophobic interface