Hydrolysis of Adenosine 5'-Triophosphate: An Isotope-Labeling Study

Article abstract of DOI:10.1021/ja00389a055

We have used a combination of 18O-labeling experiments and kinetic studies to clarify the nonenzymatic hydrolytic pathways of adenosine-5'-triphosphate (ATP) at pH values ranging from 0 to 8.3.In 1 N and 0.1 N HCl, the data are consistent with the hypothesis that hydrolysis occurs by addition-elimination, with initial attack 93percent γ and 7percent β; both lead only to ADP + P_i.In the subsequent hydrolysis of the ADP to AMP + P_i, attack is 83percent β and 17percent α.At pH 8.3, the data are consistent with the hypothesis that hydrolysis occurs by elimination-addition.Over the entire pH range studied, we detected no oxygen exchange between water and ATP, ADP, or P_i.Nonenzymatic hydrolysis and isotopic analysis of the resultant P_i comprise a preferred means of assaying the isotopic enrichment of <γ-18O>ATP to be used in studies of enzymatic processes.