In Silico Screening of Pyridinium-based Aqueous Ionic Liquid-Water Cosolvents for Lipase Catalyzed Esterification Reaction to Synthesize Dimethyl Itaconate
Oktavianus Hendra Cipta, Anita Alni, Made Puspasari Widhiastuty, Rukman Hertadi

Bandung Institute of Technology

Abstract

Dimethyl itaconate is an ester derivative of itaconic acid. The main role of dimethyl itaconate is to be a monomer for polyester synthesis. One of the method that can be used for dimethyl itaconate synthesis is to use a biocatalyst that has an advantage in the specificity of the reaction product. One of the enzymes that have been used as a biocatalyst for dimethyl itaconate synthesis is lipase. Lipase can catalyze the esterification between itaconic acid and methanol to dimethyl itaconate when using a non-aqueous solvent, whereas itaconic acid has very low solubility in non-aqueous solvent. The alternative that can be used in this problem is ionic liquids.

The ionic liquid that will be used in this study is a pyridinium based ionic liquid, which has been proven to increase esterification activity and the specificity of the product. Pyridinium based ionic liquid is more easily degraded so that it is more environmentally friendly than imidazolium based ionic liquid that have been used in previous study. Using computational study to screening which ionic liquid is compatible with lipase is very useful so we can synthesize only the most compatible ionic liquid. Itaconic acid docked to lipase catalytic site and then using molecular dynamics simulation to simulate the complex in ionic liquid-water co-solvent system. Final trajectory from molecular dynamics simulation used as starting conformation for quantum calculations using orca. Optimization energy calculation from itaconic acid substrate that get docked into lipase in water is around -491.5 HF and in 4-tetrafluoroborate pyridinium ionic liquid-water system is around -515 HF which lower than optimization energy in water. From this founding we hope 4-tetrafluoroborate pyridinium can help lipase to catalyze itaconic acid substrate. Other ionic liquid variation can be calculated too so the data can be more reliable.

Keywords: quantum chemistry, docking, molecular dynamics, lipase, ionic liquid

Topic: Theoretical and Computational Chemistry