The synthesis of fluorine-labeled analogs of the inhibitors LY333531, LY317644, and staurosporine are proposed for use as fluorine-NMR probes for protein kinase C (PKC). LY333531 is a 14-membered ring macrocyclic bisindolylmaleimide (MBIM) that is highly selective for the beta-isoform of PKC. LY333531 has recently been shown to normalize PKC-betaII activity and to ameliorate diabetic complications in vivo. LY317644 is a fifteen-membered ring macrocyclic biindolylmaleimide that is very selective for PKC over calcium calmodulin-dependent protein kinase. Staurosporine is an indolocarbazole alkaloid with an interesting pyranose bis-N-glycoside ring system. Staurosporine is a potent but unselective protein kinase inhibitor that has seen widespread use in biochemical studies. These compounds are being prepared as NMR probes as part of a long term collaborative project to determine the structural basis for the ATP-competitive, isoform-selective inhibition of PKC by LY333531. Selecting inhibitors with a range of structural elements and selectivity profiles will provide the best opportunity to detect common and unique features of the catalytic domains of PKC isoforms. The conformation of these flexible compounds while bound to each isoform of PKC, as determined from differences in the activity of diasteriomeric fluoride analogs in conjunction with structure-activity relationships, or directly from experimental studies on protein-inhibitor complexes, will provide insight into the geometry of the binding site. The synthesis of the MBIM are based on a common route developed in the PI's laboratories. The synthesis of the staurosporine analogs are based on an original synthetic approach which has the potential to address interesting issues in the synthesis of indolocarbazole alkaloids, in particular with respect to the lactam regiochemistry and the bis-N-glycoside stereochemistry. The biological activity against several PKC isoforms will be determined for each compound. An NMR solution conformation study of both diastereomers of 5'-fluorostaurosporine will be performed to determine the magnitude of the vicinal F19-H1 and F19-C13 coupling constants corresponding to the chair and boat conformers, and to determine the effect of the fluorine on the solution conformation.
