The mechanism of ATP-G-actin hydrolysis in Mg^sup 2+^-containing solutions

NMR proton spectra were recorded in the range of proton resonance in the nucleotide aromatic ring of monomeric ATP-G-actin and the Mg2+-ATP-G-actin solutions in D2O to study the mechanism of ATP-G-actin hydrolysis and its role in F-actin formation in Mg2+-containing solutions. The experimental data show variations in the proton chemical shifts of the H2 and H8 peaks and splitting of the H8 resonance peak of G-actin-bound ATP adenine caused by interaction with magnesium dication. The observed variations in spectra are explained by hydrolysis of monomeric ATP-G-actin to ADP-G-actin, which is regarded as the initial stage of the G-actin to F-actin transformation.