Hydrolysis studies of phosphodichloridate and thiophosphodichloridate ions.

We report the pH-k(obs) profiles for the hydrolyses of phosphodichloridate and thiophosphodichloridate ions in aqueous solutions. Both species show broad pH-k(obs) plateaus that extend to high pHs.

peri-Dimethylamino substituent effects on proton transfer at carbon in α-naphthylacetate esters: a model for mandelate racemase.

The rate constants for exchange of hydrogen for deuterium at the α-CH(2) positions of 8-(N,N-dimethylaminonaphthalen-1-yl)acetic acid tert-butyl ester 1 and naphthalen-1-ylacetic acid tert-butyl ester 2 have been determined in potassium deuteroxide solutions in 1 : 1 D(2)O : CD(3)CN, in order to quantify the effect of the neighbouring peri-dimethylamino substituent on α-deprotonation. Intramolecular general base catalysis by the (weakly basic) neighbouring group was not detected. Second-order rate constants, k(DO), for the deuterium exchange reactions of esters 1 and 2 have been determined as 1.

Single atom modification leads to enhanced nucleotide self-assembly: the role of cation bridging.

We report that the ability of disodium 5'-deoxy-5'-thioguanosine-5'-monophosphate, Na(2)(5'-GSMP), to self-associate into a helical G-quadruplex structure in aqueous solution at pH 8 is significantly higher than that of disodium guanosine-5'-monophosphate, Na(2)(5'-GMP), which supports our earlier hypothesis regarding the importance of cation bridging.