Enzyme–Support Interactions of Burkholderia cepacia Lipase Immobilized on Silica Using Molecular Docking and Multitechnique Characterization

Abstract

The influence of the microenvironment within enzyme–support complexes on the activity of Burkholderia cepacia lipase (BCL) immobilized on silica (SiO2–BCL) remains insufficiently understood. Without data on these interactions, it is challenging to determine whether modifications to the support material or immobilization protocols are needed for optimal enzyme activity and stability. Besides evaluating catalytic performance in esterification reactions, enzyme–support interactions were characterized using29Si NMR, FTIR, BET, DSC, TGA, SEM–EDS, and molecular docking simulations. In this study, NMR29Si-based structural analysis revealed significant protein–surface (pore wall) interaction networks. The immobilization resulted in 88.6% efficiency and a protein loading of 17.72 mg·g–1, enabling further structural and functional characterization. Molecular docking elucidated the interaction mechanisms between silica functional groups (Qnsites) and BCL binding residues. Docking simulations indicated that the Q3 group interacts with the catalytic residue Ser87, potentially hindering substrate access to the active site. Spectroscopic and morphological analyses confirmed this interaction and correlated it with a significant decrease in enzymatic activity. Experimental evidence and FTIR analyses demonstrated that the increase in the α-helix content of SiO2–BCL correlated with the observed decrease in catalytic productivity. BCL exhibited a significantly higher esterification productivity (150.82 μmol·h–1·mg–1) than SiO2–BCL (28.10 μmol·h–1·mg–1), confirming the importance of optimal enzyme conformation for catalytic efficiency. The results highlight that, beyond the support’s composition, the spatial orientation and specific interactions with functional groups are critical determinants of catalytic efficiency. This integrative approach may guide the rational design of enzyme-based biocatalysts using mesoporous materials.