Structure-activity relationships of Candida rugosa lipase immobilized on polylactic acid nanoparticles

Interfacing proteins with nanostructured materials offers the possibility to obtain novel bioconjugates for many applications. We report herein the ability of nanostructured poly-DL-lactic acid (PDLLA) based carriers to enhance enzymatic activity and stability. PDLLA was processed using an innovative patented methodology that permitted to obtain spherical nanoparticles with an average diameter of 220 nm that were used as carrier for the physical adsorption of Candida rugosa lipase (CRL). Enzymatic activity and stability of CRL before and after conjugation to the nanopolymeric support were evaluated in different conditions (pH, T, organic solvents) and the conformational changes of CRL produced by its interaction with the nanopolymeric carrier were investigated by using Fourier Transform Infrared (FTIR) spectroscopy. A comparative study between X-ray diffraction data in the literature and experimental FTIR results gave deeper insight into the conformational features of the immobilized protein.