Binding parameters for the interaction between Candida rugosa lipase and DPPC liposomes

Abstract

The binding interactions of Candida rugosa lipase (CRL) to dipalmitoylphosphatidylcholine (DPPC) liposomes in light of this lipase's aggregation behavior were characterized. The affinity of CRL aggregates for DPPC liposomes was higher than the affinity of CRL monomeric forms. The specific activity of CRL aggregates was higher than that of the monomeric form. It is possible that enzyme aggregates provide a hydrophobic environment for lipase catalysis, leading to an enhancement in lipase activity. This activation mechanism would be similar to lipase interfacial activation upon binding to an oil–water interface. Both the number of lipid molecules associated with a lipid–enzyme complex and the number of enzyme binding sites doubled when lipase concentration was increased from 2.27 to 10.33 μg/ml. Neither a change in the phase transition temperature nor a broadening of the phase transition was detected as a result of the CRL–DPPC liposome interactions. Fluorescence resonance energy transfer spectroscopy proved to be a rapid and efficient method for the determination of lipase–liposome binding parameters.