Lipase Structure in Organic Solvents Examined by Uv-Vis Spectroscopy

Enzymes are biological catalysts that accelerate the rate of reactions while experiencing no permanent chemical modifications as a result of their involvement. One industrial enzyme of interest is lipase, a water-insoluble enzyme that catalyzes the hydrolysis of ester bonds in fats or oil substrates. The catalytic activity of lipase is dependent upon its three-dimensional enzymatic structure, as well as the local solvent properties, such as polarity, hydrogen-bonding potential, and dielectric constant. In this project, porcine pancreas lipase (PPL) is incubated in various industrial organic solvents, extracted into an aqueous solution, and analyzed by ultraviolet-visible (UV- vis) spectroscopy. The degree of lipase unfolding, or denaturing, is revealed through light adsorption at 290 nm (A290) by amino acid residues located at the hydrophobic enzyme surface. Our goal is to relate lipase stability, as determined by A290 measurements to previous investigations of catalytic activity and determine optimal reaction conditions and solvent choice. Results will be further compared to corresponding examinations of lipase stability in supercritical carbon dioxide (scCO2) to determine the efficacy of scCO2 as an environmentally benign solvent medium for biocatalysts.