Diacylglycerol production by genetically modified lipase from Malassezia globosa

Diacylglycerol (DAG)-enriched oil has drawn considerable attention for the prevention of obesity and other lifestyle-related diseases. In this study, a mutant lipase of SMG1 (SMG1-F278D) from Malassezia globosa was studied for the production of DAG. The SMG1-F278D exhibited 4-fold increased esterification activity as well as superior fatty acid (FA) specificity for medium chain FAs. Molecular docking study suggested that the caprylic acid (CA) was strongly bound to the catalytic residue Ser171 present in the SMG1-F278D as compared to SMG1. Molecular Dynamics (MD) simulations were employed in order to understand the structural conformations of SMG1 and SMG1-F278D. The structure of SMG1-F278D was found to be more compact as well as less deviated from its native conformation. There was an increase in β-sheet as well as α-helix in the SMG1-F278D that may stabilize the protein structure due to point mutation. Finally, the capability of SMG1-F278D in synthesis of DAG was evaluated. Effects of reaction parameters such as substrate molar ratio of glycerol to FAs, enzyme loading and reaction temperature on the esterification were investigated. The optimal reaction conditions were achieved as 4:1 molar ratio of glycerol to FAs, enzyme loading of 100 U/g (U/w, with respect to the total substrates) and temperature of 25 °C. The present study provides important information about SMG1 mutant for better utilization in the oils and fats industries.