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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Enzyme Microheterogeneous Hydration and Stabilization in Supercritical Carbon Dioxide

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Silveira, Rodrigo L. [1] ; Martinez, Julian [2] ; Skaf, Munir S. [1] ; Martinez, Leandro [3]
Total Authors: 4
[1] Univ Estadual Campinas, Inst Chem, Campinas, SP - Brazil
[2] Univ Estadual Campinas, Fac Food Engn, Campinas, SP - Brazil
[3] Univ Sao Paulo, Inst Phys Sao Carlos, Sao Carlos, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Journal of Physical Chemistry B; v. 116, n. 19, p. 5671-5678, MAY 17 2012.
Web of Science Citations: 26

Supercritical carbon dioxide is a promising green-chemistry solvent for many enzyme-catalyzed chemical reactions, yet the striking stability of some enzymes in such unconventional environments is not well understood. Here, we investigate the stabilization of the Candida antarctica Lipase B (CALB) in supercritical carbon dioxide-water biphasic systems using molecular dynamics simulations. The preservation of the enzyme structure and optimal activity depend on the presence of small amounts of water in the supercritical dispersing medium. When the protein is at least partially hydrated, water molecules bind to specific sites on the enzyme surface and prevent carbon dioxide from penetrating its catalytic core. Strikingly, water and supercritical carbon dioxide cover the protein surface quite heterogeneously. In the first solvation layer, the hydrophilic residues at the surface of the protein are able to pin down patches of water, whereas carbon dioxide solvates preferentially hydrophobic surface residues. In the outer solvation shells, water molecules tend to cluster predominantly on top of the larger water patches of the first solvation layer instead of spreading evenly around the remainder of the protein surface. For CALB, this exposes the substrate-binding region of the enzyme to carbon dioxide, possibly facilitating diffusion of nonpolar substrates into the catalytic funnel. Therefore, by means of microheterogeneous solvation, enhanced accessibility of hydrophobic substrates to the active site can be achieved, while preserving the functional structure of the enzyme. Our results provide a molecular picture on the nature of the stability of proteins in nonaqueous media. (AU)

FAPESP's process: 10/16947-9 - Correlations between dynamics, structure and function in protein: computer simulations and algorithms
Grantee:Leandro Martinez
Support type: Regular Research Grants
FAPESP's process: 10/08680-2 - Molecular aspectos of lignocellulosic biomass degradation: dynamics of enzymes and plant cell wall nanoarchitecture
Grantee:Rodrigo Leandro Silveira
Support type: Scholarships in Brazil - Doctorate