FAST-ATOM-BOMBARDMENT TANDEM MASS-SPECTROMETRY OF CYCLIC-NUCLEOTIDE ANALOGS USED AS SITE-SELECTIVE ACTIVATORS OF CYCLIC NUCLEOTIDE-DEPENDENT PROTEIN-KINASES

The mass spectrometric behaviour of six cyclic nucleotide analogues wh ich activate cyclic AMP-dependent protein kinase was studied by positi ve-ion fast-atom bombardment (FAB) and collision-induced dissociation (CID) mass-analysed ion kinetic energy (MIKE) spectrometry, The compou nds studied were 1,N-6-ethenoadenosine-3',5'-cyclic monophosphate (eps ilon-cyclic AMP) and 2'-aza-1,N-6-ethenoadenosine-3',5'-cyclic monopho sphate, which each activate both isoforms of cyclic AMP-dependent prot ein kinase and have similar affinity for both the 'fast' and the 'slow ' regulatory site of each isoform, N-6-phenyl-cyclic AMP, which is sel ective for the 'fast' regulatory site of each isoform, and 6-chloropur ine riboside-3',5'-cyclic monophosphate, o-1-beta-D-ribofuranosylbenzi midazole-3',5'-cyclic monophosphate and 8-(4-chlorophenylthio)-adenosi ne-3',5'-cyclic monophosphate, which are each selective for the 'slow' regulatory site and preferentially activate isoform II. The FAB-and C ID/MIKE spectra of the analogues are discussed in relation to their us e in studies of the regulation of protein kinase activity by quantitat ive FAB mass spectrometry. (C) 1998 John Wiley & Sons, Ltd.