Synthesis of decanoate compounds in deep eutectic solvent using lipase: Optimization using response surface methodology, kinetic and docking study

In the present study,the synthesis of decanoate esters by immobilized lipase in deep eutectic solvent (DES) was investigated, and a suitable kinetic model was suggested. Initially, various DES and lipase were screened to synthesize propyl decanoate; out of that, Glycerol:Choline chloride (Gly:ChCl) and Candida antarctica lipase B (Cal B) was found to be the best DES and lipase, respectively. Response surface methodology (RSM) with a five-factor-three-level central composite design was applied to optimize various reaction variables. The activation energy was derived using the Arrhenius graph, which was 14.59 kcal/mol. The catalyst recycling study showed that biocatalysts could be recycled up to four cycles. The reaction kinetics was studied, and the reaction followed the Ping Pong Bi Bi mechanism. We carried out molecular docking to find out confirmation of substrates and their binding site in the Cal B. It was concluded that acylation of active site serine residue is a favorable step in the reaction mechanism. Furthermore, strong hydrogen bonding was observed between the substrate and active site that is serine and histidine.