Thiophosphate analogs of c-di-GMP: impact on polymorphism.

Seven phosphorothioate analogs of c-di-GMP (all diastereomers of mono-, di-, and trithiophosphates) were prepared to assess the impact of the thioate substitutions on c-di-GMP polymorphism using 1D (1)H and (31)P NMR, along with 2D NOESY and DOSY, for both the Na(+) and K(+) salts. The K(+) salts display more extensive higher order complex formation than the Na(+) salts, resulting primarily in octamolecular complexes with K(+), but tetramolecular complexes with Na(+). Further, the presence of one or two [S(P)] sulfurs specifically stabilizes anti complexes and/or destabilizes syn complexes, while the presence of two [S(P)] sulfurs promotes extensive aggregation.