Action of 3 tyrphostin derivatives on casein kinase II from rat liver.

AIM

To study the action of tyrphostin on casein kinase (CK) II.

METHODS

CK II was partially purified from rat livers by sequential DE52 and heparin-Sepharose chromatography. CK II activity was assayed by incubating CK II with dephosphorylated casein and [gamma-32P]ATP.

RESULTS

AG34 inhibited the activity of CK II with IC50 33 (27-41) mumol.L-1. Both AG372 (121 mumol.L-1) and AG1112 (150 mumol.L-1) displayed inhibitory effects on the activity of CK II. Kinetic studies of AG34 on CK II showed that it was noncompetitive with casein and ATP.

CONCLUSION

AG34, AG372, and AG1112 were potent inhibitors of CK II, and the inhibitory action of AG34 was noncompetitive with casein and ATP.