A recombinant cutinase from Fusarium solani pisi was immobilized by adsorption/deposition onto several zeolites. These preparations were used to catalyse the alcoholysis of butyl acetate with hexanol in isooctane. Ground state diffuse reflectance measurements were performed for the preparations previously equilibrated with salt solutions at well-defined optimum water activity. The corresponding cutinase fluorescence emission spectra were used to detect different conformational enzyme states, induced by different zeolite properties. Significant conformational changes were observed, with important consequences on the enzymatic activities.