How Enzyme Selectivity and Immobilization Affect Catalytic Yields in Lipase-Catalyzed Processes

Abstract: Herein, the influence of structural attributes, including the interactions of lipases with support systems, substrates, products/byproducts, and the media environment, on enzyme stability, selectivity and activity are discussed. Substrates/products, such as methanol, glycerol, phenolic acids and polyphenols, can inhibit lipase activity by influencing the mass flow of the reactants and products or by enzyme denaturation, which is also caused by extreme pH, high temperatures, and digestive action of most organic solvents. Immobilization techniques that involve chemical bonding between the functional groups of the support and the amino acids of the lipase maintain the enzyme’s active conformation via the formation of stable secondary structures. Functionalized metal nanoparticles and metal and covalent organic frameworks (COFs and MOFs) covalently bond to lipases, reducing the reliance of the active site conformation on hydrogen bonding and disulfide bonds. The crystallinity of COFand MOF-immobilized lipases allows them to be used in contrasting media environments and at high temperatures, which increases the reaction kinetics and improves the catalytic yield. On the other hand, inert support systems such as silica promote catalytic yields by minimizing protein leaching, which fairly maintains the amount of the preloaded lipase. The structure of substrates also plays a large role, whereas some lipases strictly prefer narrow substrates. In contrast, others, such as Candida species lipases, are liberal and allow substrates of varying bulkiness/steric hindrances.