Improvements in the radiometric assay of adenosine triphosphate and its application in the reverse isotope dilution analyses of 14C-labelled sugars

The hexokinase: 14C-labelled hexose: adenosinetriphosphate system described earlier for the estimation of adenosine triphosphate (ATP) and 14C labelled glucose, fructose and mannose was modified to achieve a greater than ten-fold reduction in the quantities assayed and to improve the assay precision. In the modified procedure the incubation volumes were reduced and the resin bound hexose phosphate was directly counted after extraction with 4N sulphuric acid. Thus, only single counting needs to be performed per assay tube. ATP assays can now be performed in the 0.02 to 1 nM range and specific activity of the epimeric labelled hexoses can be carried out with less than a microgram of the substance. (author)