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Enzyme microheterogeneous hydration and stabilization in supercritical carbon dioxide
Rodrigo L Silveira1, Julian Martínez, Munir S Skaf
1Institute of Chemistry, and ‡Faculty of Food Engineering, State University of Campinas , Campinas, SP, Brazil.
The Journal of Physical Chemistry. B
|April 14, 2012
Summary
Supercritical carbon dioxide stabilizes enzymes like Candida antarctica Lipase B (CALB) when water is present. This water forms protective patches, preserving enzyme structure and enhancing substrate access for green chemistry applications.
Area of Science:
- Biochemistry and Green Chemistry
- Computational Chemistry and Molecular Dynamics
Background:
- Supercritical carbon dioxide (scCO2) is a green solvent for enzyme catalysis.
- Enzyme stability in scCO2 is not fully understood.
- Candida antarctica Lipase B (CALB) is a key enzyme for industrial applications.
Purpose of the Study:
- Investigate the stabilization mechanism of CALB in scCO2-water biphasic systems.
- Understand the role of water in preserving enzyme structure and activity.
- Elucidate the molecular interactions governing enzyme stability in non-aqueous media.
Main Methods:
- Molecular dynamics simulations were employed.
- The study focused on CALB in scCO2-water mixtures.
- Analysis of protein hydration and solvent distribution was performed.
Main Results:
- Enzyme stability and activity depend on the presence of water.
- Water molecules bind to specific sites, preventing scCO2 penetration into the catalytic core.
- Heterogeneous solvation by water and scCO2 was observed, with preferential binding to hydrophilic and hydrophobic residues, respectively.
- Outer water shells clustered, exposing the substrate-binding region to scCO2.
Conclusions:
- Microheterogeneous solvation enhances hydrophobic substrate accessibility to CALB's active site.
- The functional structure of CALB is preserved in scCO2-water systems.
- This provides a molecular understanding of protein stability in non-aqueous environments, crucial for green chemistry.
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