Cutinase binding and activity at the triolein–water interface monitored by oil drop tensiometry

Changes of the oil–water interfacial tension resulting from binding of Fusarium solani pisi cutinase and subsequent lipid hydrolysis were investigated using the oil drop technique. An ELISA was developed to determine the amount of cutinase bound to the triolein–water interface after biotinylation of the enzyme. Cutinase irreversibly adsorbs to a maximum value of about 2 mg/m 2. A minimal specific activity of 110 μmol/min/mg was calculated for cutinase acting on a single oil droplet, which is close to the activity found for triglyceride emulsions. At a maximum surface load cutinase could generate one monolayer of fatty acid products per second at the interface. It was found that oleic acid rapidly dissolves into the oil phase under the conditions used. The interfacial tension measured reflects the adsorption of cutinase to the oil droplet and also responds to the fate of the hydrolysis products. A model is presented that describes the catalytic events at the oil–water interface during lipid hydrolysis.