ASSAY OF ADENOSINE 3',5'-CYCLIC MONOPHOSPHATE-DEPENDENT PROTEIN-KINASE ACTIVITY BY QUANTITATIVE FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY

Cyclic AMP-dependent protein kinase is conventionally assayed by measu ring the incorporation of radiolabeled phosphate into a histone substr ate. Here the assay of the protein kinase is carried out by the positi ve-ion fast atom bombardment mass spectrometric analysis of the enzyme incubation mixture after the reaction has been terminated. The data o btained are in good agreement with those obtained from the conventiona l radiometric assay of the same kinase preparation. The inherent advan tage of this mass spectrometric assay is the capacity for multiple com ponent monitoring; in addition to the kinase activity, the ability of the enzyme to bind cyclic nucleotides, together with integral ATPase a nd phosphodiesterase activity, can also be estimated from the same spe ctra. (C) 1995 Academic Press, Inc.