Lipase Activation by Poly(Methyl Methacrylate) in Dispersed Solution: Mechanistic Insights by Fluorescence Spectroscopy.

We investigated the mechanisms of polymer-lipase interactions that govern the catalytic activity of lipases in the presence of polymers. Using a combination of fluorescence correlation spectroscopy (FCS), activity analysis, fluorescence spectroscopy, and computational surface analysis, three model lipases-Thermomyces lanuginosus lipase (TLL), Candida antarctica lipase B (CalB), and Bacillus subtilis lipase A (BSLA), with different degrees of hydrophobic active site exposure were studied. Low-molecular-weight poly(methyl methacrylate) (PMMA), synthesized via ARGET ATRP, was employed to study the effect of unstructured polymers in dispersed solution on lipase activity. PMMA significantly enhanced TLL and BSLA hydrolytic activity, while no CalB activation was observed. FCS analysis indicated that this activation was facilitated by polymer lipase binding, a phenomenon observed with TLL and BSLA but not with CalB. Computational analysis further revealed that the surface properties of the lipases were critical for the lipases' susceptibility to activation by PMMA. Although CalB exhibited the largest total hydrophobic surface area, its homogeneous distribution prevented activation, whereas strong, localized hydrophobic interactions allowed PMMA to bind and activate TLL and BSLA. Supported by the quantitative correlation between elevated 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence in the presence of PMMA and lipase activity, the activation was attributed to locally increased hydrophobicity of the lipases upon polymer binding. These findings provide critical insights into the role of polymer interactions in lipase activation and stabilization, highlighting the potential for designing tailored polymer carriers to optimize enzyme performance in industrial and biotechnological applications.