Inhibition of cyclic AMP-dependent protein kinase-induced changes in the kinetic properties of hepatic pyruvate kinase by the specific cyclic AMP antagonist, the (Rp)-diastereomer of adenosine cyclic 3',5'-phosphorothioate.
The effects of the diastereomers of adenosine cyclic 3',5'-phosphorothioate, (Sp)- and (Rp)-cAMPS, on the kinetic properties of pyruvate kinase were studied in hepatocytes isolated from fed rats. Incubation of the cells with the cAMP-dependent protein kinase agonist, (Sp)-cAMPS, produced a concentration-dependent increase in S0.5 for phosphoenolpyruvate, but had no effect on Vmax. The (Sp)-cAMPS-treated enzyme was more sensitive to inhibition by alanine and ATP and, under the same conditions, was less responsive to activation by fructose-1,6-bisphosphate when assayed at a subsaturating phosphoenolpyruvate concentration. Incubation of the hepatocytes with only the cAMP-dependent protein kinase antagonist, (Rp)-cAMPS, produced no change in any kinetic parameters, but did suppress the (Sp)-cAMPS- or glucagon-induced increase in the S0.5 for phosphoenolpyruvate with IC50 values of 10 microM and 5 microM (Rp)-cAMPS. (Rp)-cAMPS is exerting an effect on the kinetic properties of pyruvate kinase through inhibition of cAMP-dependent protein kinase.
Dragland-Meserve
C J
CJ
Rothermel
J D
JD
Houlihan
M J
MJ
Botelho
L H
LH
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000409:Alanine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005934:Glucagon / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D011770:Pyruvate Kinase / Q000378:metabolism*; D051381:Rats; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013873:Thionucleotides / Q000494:pharmacology*
D047428:Protein Kinase Inhibitors; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D005934:Glucagon; D000242:Cyclic AMP; D011770:Pyruvate Kinase; D000409:Alanine