Unraveling Lipase’s Promiscuous Behavior: Insights into Organic Acid Inhibition during Solventless Ester Production

Production of esters using chemical catalysts often entails off-odors, colors, or environmentally harmful reagents. Lipases play a pivotal role in enhancing product purity and sustainability. Despite their acknowledged substrate promiscuity, quantitative characterization of biocatalytic ester production remains scarce. Moreover, their behavior in solvent-free conditions, particularly in the presence of potentially inhibitory organic acids, is unknown. A systematic quantitative approach was conducted, which culminated in the development of a substrate preference heat map. A subsequent in-depth examination led to the identification and validation of a novel rate equation. While mechanistic in nature, an empirical adjustment is incorporated to account for inhibition effects. Specifically, this adjustment involves raising the acid concentration within the inhibition term to the power of n. This advancement is poised to facilitate scale-up endeavors to produce biocatalytic esters derived from short-chain fatty acids.