Conformation of adenosine-5′-triphosphate in the presence of Mg 2+ at different pH

Abstract

NOESY experiments have been performed on adenosine-5′-triphosphate (ATP) in the presence of 1:1 Mg 2+ (MgCl 2) at different pH. The results show that H8H1′ and H8H2′ interproton NOE intensities change with pH, with nearly equal intensity at low pH (pH 1.9) and with H8H2′ signal stronger than the H8H1′ signal at higher pH (between 3.7 and 8.5). The H8H1′ and H8H2′ distances and the C4N9C1′O4′ torsion angle ( χ) have been measured from random structures of adenosine and ATP. It is concluded that the lower pH allows the formation of a P γ OMg 2+N1 bridge and the torsion angle takes a cis conformation accordingly.