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Extensive counter-ion interactions seen at the surface of subtilisin in an aqueous medium
| Content Provider | Semantic Scholar |
|---|---|
| Author | Cianci, Michele Negroni, Jacopo Helliwell, John R. Halling, Peter J. |
| Copyright Year | 2014 |
| Abstract | The extent of protein and counter-ion interactions in solution is still far from being fully described and understood. In low dielectric media there is documented evidence that counter-ions do bind and affect enzymatic activity. However, published crystal structures of macromolecules of biological interest in aqueous solution often do not report the presence of any counter-ions on the surface. The extent of counter-ion interactions within subtilisin in an aqueous medium has been investigated crystallographically using CsCl soak and X-ray wavelength optimised anomalous diffraction at the Cs K-edge. Ten Cs+, as well as six Cl− sites, have been clearly identified, revealing that in aqueous salt solutions ions can bind at defined points around the protein surface. The counter-ions do not generally interact with formal charges on the protein; formally neutral oxygens, mostly backbone carbonyls, mostly coordinate the Cs+ ions. The Cl− ion sites are also found likely to be near positive charges on the protein surface. The presence of counter-ions substantially changes the protein surface electrical charge. The surface charge distribution on a protein is commonly discussed in relation to enzyme function. The correct identification of counter-ions associated with a protein surface is necessary for a proper understanding of an enzyme's function. |
| Starting Page | 36771 |
| Ending Page | 36776 |
| Page Count | 6 |
| File Format | PDF HTM / HTML |
| DOI | 10.1039/C4RA06448H |
| Alternate Webpage(s) | https://pure.strath.ac.uk/ws/portalfiles/portal/45266019/Cianci_etal_RSCA_2014_Extensive_counter_ion_interactions_seen_at_the_surface_of_subtilisin.pdf |
| Alternate Webpage(s) | https://strathprints.strath.ac.uk/54816/1/Cianci_etal_RSCA_2014_Extensive_counter_ion_interactions_seen_at_the_surface_of_subtilisin.pdf |
| Alternate Webpage(s) | https://doi.org/10.1039/C4RA06448H |
| Volume Number | 4 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
