Molecular dynamics investigation of the ionic liquid/enzyme interface: application to engineering enzyme surface...

Area of Science:

• Biochemistry and Molecular Biology
• Computational Chemistry
• Biotechnology

Background:

• Enzyme stability in ionic liquids (ILs) is crucial for biocatalysis.
• Chemical modification, like succinylation, can enhance enzyme stability in ILs.
• Understanding enzyme-IL interactions at a molecular level is key.

Purpose of the Study:

• To investigate how altering enzyme surface charge affects interactions with aqueous ionic liquids.
• To provide molecular insights into the enhanced stability of modified enzymes in ILs.
• To correlate changes in surface charge with specific ionic liquid substituent organization.

Main Methods:

• Molecular dynamics simulations of Candida rugosa lipase and Bos taurus α-chymotrypsin.
• Enzyme surface charge modification through lysine to glutamate mutations.
• Analysis of radial distribution functions and solvent charge densities.

Main Results:

• Mutating surface residues decreased net enzyme charge, increasing local solvent charge density.
• Modified enzymes showed reduced interactions with IL anions and increased cation contact.
• The influence of altered enzyme charge on IL organization was short-ranged (≤1 nm).

Conclusions:

• Enzyme surface charge significantly modulates enzyme-IL interactions.
• Short-range ordering of IL constituents is influenced by enzyme surface charge.
• These findings offer molecular-level understanding supporting experimental observations on enzyme stability in ILs.