Unique inhibitory action of the synthetic compound 2-[N-(2-aminoethyl)-N-(5-isoquinolinesulfonyl)] amino-N-(4-chlorocinnamyl)-N-methylbenzylamine (CKA-1306) against calcium/calmodulin-dependent protein kinase I.
A newly synthesized compound, 2-[N-(2-aminoethyl)-N-(5-isoquinolinesulfonyl)]amino-N-(4-chlorocinnamyl )-N-methylbenzylamine (CKA-1306), was found to inhibit cyclic AMP-dependent protein kinase (PKA) and Ca2+/calmodulin-dependent protein kinase I (CaMK I) with IC50 values of 1.6+/-0.14 and 2.5+/-0.16 microM, respectively. In contrast, the established PKA inhibitors H-8 and H-89 inhibited CaMK I with relatively high IC50 values of >100 and 24.4+/-3.2 microM, respectively. An additional inhibitor, KN-62, against Ca2+/calmodulin-dependent protein kinase II (CaMK II) did not inhibit either PKA or CaMK I at the concentrations tested. In our library of many isoquinolinesulfonamide derivatives, only CKA-1306 inhibited CaMK I to a satisfactory degree, suggesting a unique mode of action. Indeed, the inhibition of CaMK I by CKA-1306 was competitive in every respect to Mg2+/ATP, peptide substrate (syntide-2), and Ca2+/calmodulin. This phenomenon may be understood from the context of the recently determined structure of the enzyme in its autoinhibited state. Such kinetic analysis was also extended to cases using a phosphorylated and activated enzyme at Thr177 or a constitutively active, COOH-terminal truncated mutant at Gln293. CKA-1306 still competed with Mg2+/ATP for the two enzymes, but it no longer achieved any competitive advantage over syntide-2. These results may reflect some differences in the active conformation of CaMK I. However, the compound should be constant in its recognition of an Mg2+/ATP-binding site of the enzyme. Though CKA-1306 is not specific to CaMK I, the compound will be useful in studying the enzyme further under limited conditions.
Sakaguchi
H
H
Department of Pharmacology, Nagoya University School of Medicine, Japan.
Yokokura
H
H
Terada
O
O
Naito
Y
Y
Nimura
Y
Y
Hidaka
H
H
D000818:Animals; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D002417:Cattle; D002934:Cinnamates / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology*; D007700:Kinetics; D013449:Sulfonamides
C114521:CKA-1306; D002934:Cinnamates; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D013449:Sulfonamides; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide