Interactions between 2,2-dimethyl-2-silapentane-5-sulfonate and nucleoside 5′-monophosphates in aqueous solution

✍ Scribed by Barbara L. Sagan; Judith A. Walmsley

• Book ID: 102528955
• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 456 KB
• Volume: 25
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260250308

✦ Synopsis

Hydrophobic binding of 2,2-dimethyl-2-silapentane-5-sulfonate (DSS) to guanosine 5'-monophosphate (5'-GMP) and cytidine 5'-monophosphate (5'-CMP) results in an upfield shift of the 'H NMR trimethylsilyl resonances with respect to an internal reference tetramethylammonium ion. The nature of the nucleotideDSS interaction and the stability of the resulting complexes have been studied. The magntiude of the effect is dependent on the nature and extent of the self-association of the nucleotide and the nucleotide concentration. For nucleotides which self-associate non-cooperatively to form disordered base stacks, such as Liz(5'-GMP) and M2(5'-CMP), where M = Li+, Na+, K+ and Rb+, the formation of 2:l complexes (nucleotide to DSS molar ratio) has been proposed. Apparent equilibrium constants for the 2: 1 complexes are 0.44 M-' for Li,(S-GMP) at 2 "C and an average value of 0.30 M-' for Mz(5'-CMP) at 1 "C. For the Na+ and Rb+ salts of 5'-GMP, which form strongly associated, ordered self-aggregates, the interaction between DSS and 5'-GMP is considerably reduced owing to the inability of DSS to compete effectively with the self-aggregation process.