Molecules 2012, 17(2), 1870-1882; doi:10.3390/molecules17021870
Article

Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis

1email, 2email, 3email and 2,* email
Received: 27 October 2011; in revised form: 7 February 2012 / Accepted: 7 February 2012 / Published: 14 February 2012
(This article belongs to the Special Issue Enzyme-Catalyzed Reactions)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: The potential of enzyme catalysis in organic solvents for synthetic applications has been overshadowed by the fact that their catalytic properties are affected by organic solvents. In addition, it has recently been shown that an enzyme’s initial activity diminishes considerably after prolonged exposure to organic media. Studies geared towards understanding this last drawback have yielded unclear results. In the present work we decided to use electron paramagnetic resonance spectroscopy (EPR) to study the motion of an active site spin label (a nitroxide free radical) during 96 h of exposure of the serine protease subtilisin Carlsberg to four different organic solvents. Our EPR data shows a typical two component spectra that was quantified by the ratio of the anisotropic and isotropic signals. The isotropic component, associated with a mobile nitroxide free radical, increases during prolonged exposure to all solvents used in the study. The maximum increase (of 43%) was observed in 1,4-dioxane. Based on these and previous studies we suggest that prolonged exposure of the enzyme to these solvents provokes a cascade of events that could induce substrates to adopt different binding conformations. This is the first EPR study of the motion of an active-site spin label during prolonged exposure of an enzyme to organic solvents ever reported.
Keywords: subtilisin Carlsberg; organic solvents; EPR spectroscopy; enzyme kinetics in organic solvents
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MDPI and ACS Style

Bansal, V.; Delgado, Y.; Legault, M.D.; Barletta, G. Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis. Molecules 2012, 17, 1870-1882.

AMA Style

Bansal V, Delgado Y, Legault MD, Barletta G. Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis. Molecules. 2012; 17(2):1870-1882.

Chicago/Turabian Style

Bansal, Vibha; Delgado, Yamixa; Legault, Marc D.; Barletta, Gabriel. 2012. "Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis." Molecules 17, no. 2: 1870-1882.

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