| Autor: |
Walmsley, JudithA., Schneider, MichaelL., Farmer, PatrickJ., Cave, JeffreyR., Toth, CharlesR., Wilson, RhondaM. |
| Zdroj: |
Journal of Biomolecular Structure and Dynamics; December 1992, Vol. 10 Issue: 3 p619-638, 20p |
| Abstrakt: |
AbstractThe aggregation behavior of guanylyl-(3′-5′)-guanosine, GpG, in the form of the tetramethylammonium (TMA), Li, Na, and K salts in aqueous solution has been investigated by NMR and FTIR techniques. The salts were prepared by a cation-exchange method. The ability of the cations to induce aggregate formation is TMA+< Li+< Na+< K+, where TMA+has only a weakly promoting action and K+has a very strong effect. Three types of aggregates have been observed: (a) small aggregates which are in rapid exchange with respect to the NMR time scale; (b) intermediate-sized aggregates which are slow to exchange; (c) very large aggregates which can only be observed by FTIR. In all cases the aggregated species are held together by base stacking and guanine-guanine hydrogen bonding. A stoichiometry of 2 GpG per K+has been determined by a 1H NMR titration of TMAGpG with KCl. Models have been proposed for the various-sized species. These include stacked dimers, stacked tetramers (similar to G- tetrads), and species in which K+ion bridges between phosphates in separate tetramers. |
| Databáze: |
Supplemental Index |
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