Micro-Aqueous Organic System: A Neglected Model in Computational Lipase Design?

Area of Science:

• Biochemistry
• Biophysics
• Computational Chemistry

Background:

• Water content is crucial for lipase-catalyzed reactions in organic media.
• Its role is often overlooked in molecular dynamics (MD) simulations of lipases.
• Understanding enzyme behavior in micro-aqueous organic solvent (MAOS) media is essential.

Purpose of the Study:

• To investigate the mechanisms of lipases in MAOS media using MD simulations.
• To explore how water molecules influence lipase conformation and dynamics in organic solvents.
• To highlight the importance of microenvironment considerations in MD studies.

Main Methods:

• Molecular dynamics (MD) simulations were performed on *Candida antarctica* lipase B, *Candida rugosa* lipase, and *Rhizopus chinensis* lipase.
• Analysis included unique lipase conformations, water molecule aggregation on protein surfaces, and radial distribution functions.
• Energy landscapes and minimum energy paths were examined to understand dynamic states.

Main Results:

• Lipases exhibited distinct conformations in MAOS compared to non-aqueous systems.
• Water molecule aggregation on the lipase surface was identified as a key determinant of these conformations.
• Two distinct water shells were observed around the lipases in MAOS.
• Dynamic open states of lipases in MAOS differed from other solvent environments.

Conclusions:

• The microenvironment, particularly water content, critically influences lipase behavior in organic media.
• MD simulations must account for micro-aqueous conditions to accurately predict lipase function.
• This study underscores the necessity of considering solvent effects in enzymatic reaction simulations.