Surfactant interference on lipase catalysed reactions in microemulsions

Area of Science:

• Biocatalysis
• Surfactant Chemistry
• Enzyme Kinetics

Background:

• Lipase-catalyzed hydrolysis of palm oil is crucial for producing free fatty acids.
• Microemulsion systems offer unique environments for enzymatic reactions.
• Surfactant type significantly influences enzyme activity and reaction pathways.

Purpose of the Study:

• To compare the efficacy of nonionic (C12EO5) and anionic (AOT) microemulsion systems for lipase-catalyzed palm oil hydrolysis.
• To elucidate the reasons behind differences in reaction yield and rate between the two systems.
• To investigate the role of surfactant structure in enzyme inhibition.

Main Methods:

• Enzymatic hydrolysis of palm oil using lipase in C12EO5 and AOT microemulsions.
• Radiochromatography to quantify product yield and identify side reactions.
• Kinetic measurements to determine reaction rates.
• Analysis of microemulsion structure and interfacial properties.

Main Results:

• Significantly lower free fatty acid yield in the C12EO5 system compared to the AOT system.
• Enzymatic esterification on the nonionic surfactant (C12EO5) was identified as a cause for low yield.
• Reaction rates were approximately ten times faster in the AOT system.
• C12EO5 surfactant inhibited the enzyme by competing for the active site, unlike AOT.

Conclusions:

• Anionic AOT microemulsions are superior to nonionic C12EO5 microemulsions for lipase-catalyzed palm oil hydrolysis.
• The inhibitory effect of C12EO5 is attributed to its hydrophobic structure competing with the substrate for the enzyme's active site.
• Microemulsion structure and interfacial tension were not the primary factors determining the observed rate differences.