(Rp)- and (Sp)-8-piperidino-adenosine 3',5'-(cyclic)thiophosphates discriminate completely between site A and B of the regulatory subunits of cAMP-dependent protein kinase type I and II.
8-Piperidino-cAMP has been shown to bind with high affinity to site A of the regulatory subunit of cAMP-dependent protein kinase type I (AI) whereas it is partially excluded from the homologous site (AII) of isozyme II [Ogreid, D., Ekanger, R., Suva, R. H., Miller, J. P., and Døskeland, S. O. (1989), Eur. J. Biochem. 181, 19-31]. To further increase this selectivity, the (Rp)- and (Sp)-diastereoisomers of 8-piperidino-cAMP[S] were synthesized and analyzed for their potency to inhibit binding of [3H]cAMP to site A and site B from type I (rabbit skeletal muscle) and type II (bovine myocardium) cAMP-dependent protein kinases. (Sp)-8-Piperidino-cAMP[S] showed an enhanced relative affinity for site AI, thus being by far the best A-selective compound (more than 100-fold) tested for this isozyme. In contrast, the (Rp)-isomer was less selective for AI than 8-Piperidino-cAMP itself. The reduction in affinities for BII, compared to 8-piperidino-cAMP, were 10-fold and 50-fold for the (Sp)- and (Rp)-isomer, respectively. Both isomers were almost completely excluded from AII, with affinities about 1000-fold lower than 8-piperidino-cAMP itself. The (Rp)-isomer selected BII with an affinity about 10,000 times higher than for AII, whereas the (Sp)-isomer showed a preference of about 70,000-fold in favour of BII. 8-Piperidino-cAMP as well as its (Sp)-isomer activated both types of holoenzyme protein kinases whereas the (Rp)-isomer acted as an antagonist of cAMP-induced activation. The study concludes that the combination of piperidino- and exocyclic sulfur substitutions generate cAMP analogs that completely discriminate between site A and B of cAMP-dependent protein kinases.
Ogreid
D
D
Center of Molecular Medicine, University of Bergen, Norway.
Dostmann
W
W
Genieser
H G
HG
Niemann
P
P
Døskeland
S O
SO
Jastorff
B
B
D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000378:metabolism; D010880:Piperidines / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D010880:Piperidines; C015482:protein kinase modulator; D000242:Cyclic AMP; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases