Hydrolytic cleavage of DNA-model substrates promoted by polyoxovanadates.

Hydrolysis of 4-nitrophenyl phosphate (NPP) and bis-4-nitrophenyl phosphate (BNPP), two commonly used DNA model substrates, was examined in vanadate solutions by means of (1)H, (31)P and (51)V NMR spectroscopy. The hydrolysis of the phosphoester bond in NPP at 50 degrees C and pH 5.0 proceeds with a rate constant of 1.

When structural and electronic analogy leads to reactivity: the unprecedented phosphodiesterase activity of vanadates.

The interaction between an RNA model phosphodiester and oxovanadate complexes results in a purely hydrolytic cleavage of a phosphodiester bond under physiological pH and temperature: a comparison of the rate-pH profile with the species distribution diagram indicates that the negatively charged tetravanadate [V(4)O(12)](4-), which forms at toxic vanadium levels, is the hydrolytically active species.