Abstract
Enzymes are very sensitive and highly complex systems, exhibiting a substantial degree of structural variability in their folded state. In the presence of cosolvents, the fluctuations among vast numbers of folded and unfolded conformations occur via many different pathways, and alternatively, enzymes can be stabilized or destabilized. To understand the contribution of osmolytes and denaturants on the stabilization, related to the associated structural changes and enzyme activity of alpha-chymotrypsin (CT), we have monitored differential scanning calorimeter (DSC), circular dichroism (CD), enzyme activity, and gel electrophoresis as a function of osmolyte or denaturant concentration. The present investigation compares the compatibility of osmolytes and deleterious effects of denaturants on the structure, function, and enzyme activity of CT. This comparison has provided new important insight on the contribution of cosolvent effects on protein folding/unfolding, enzyme activity, and understanding of protein-solvent interactions. Our DSC results reveal that the enthalpy change (DeltaH) and Gibbs free energy of change (DeltaG(u)) of CT in osmolyte (trimethylamine N-oxide (TMAO), betaine, sarcosine, proline, and sucrose) increase linearly as osmolyte concentration increases, while those values decrease sharply in the presence of denaturants (urea and guanidine hydrochloride (GdnHCl)). The modifications in the secondary structure of this beta/beta protein, as quantified by the CD spectra, showed reasonable enhancement for beta-strands in the presence of the osmolytes as compared to buffer, which contributes to its stabilization power. Evidently, we observed that naturally occurring osmolytes have a dominant contribution to the stabilization of CT while not enhancing its enzyme activity. In contrast, our results revealed that the denaturants enhanced the surface of the enzyme by binding to the surface of CT, which leads to zero enzyme activity.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
