Mechanisms and rates of hydrolytic dephosphorylation of 5'-hydrogen-ph
osphonates, 5'-phosphorofluoridates, and 5'-phosphates of natural and
3'-substituted thymidines in human serum were studied. The stability o
f 5'-phosphonates of 2'-deoxy- and 2',3'-dideoxyadenosines in calf and
human sera was found.