18O-exchange by hydrolyzing enzymes: an ab initio calculation

Enzymes which hydrolyse ATP cause an exchange of 180 of labelled Pi in the presence of ADP. A theory for the evaluation of rate constants from an observation of the time dependence of the concentration of the various Pi species is presented. Application to the 180 exchange catalysed by myosin SI as observed by 31P-NMR shows excellent agreement with values of the rate constants determined earlier