[Inhibitory effect and its kinetic analysis of baicalein on recombinant human protein kinase CK2 holoenzyme].
OBJECTIVE
Protein kinase CK2 is a ubiquitous and pleiotropic Ser/Thr protein kinase in eukaryotic cells. CK2 activity has been shown to be markedly elevated in solid tumors and leukemia cells. Its alpha or alpha' gene is a protooncogene. CK2 is attracting increasing attention as a potential target for anti-neoplastic. This study was to search specific CK2 inhibitors in tumor cells through observation of the inhibitory effects of baicalein on recombinant human protein kinase CK2 holoenzyme and its kinetics in vitro.


METHODS
Recombinant human protein kinase CK2 alpha' and beta subunits were cloned and expressed by gene engineering, and purified to homogeneous. These 2 subunits were mixed at equal molar ratio to reconstitute CK2 holoenzyme. The CK2 activity was evaluated by detecting radioactivity of 32P of [gamma-32P]ATP which was incorporated into the substrate in various conditions.


RESULTS
Baicalein was shown to strongly inhibit the holoenzyme activity of CK2 with IC50 of 2.54 micromol/L. Kinetic studies of baicalein on CK2 showed that baicalein acted as an inhibitor of noncompetitive with ATP(KI=7.73 micromol/L) and mixed types with casein(KI=3.07 micromol/L).


CONCLUSIONS
Baicalein is an effective inhibitor of protein kinase CK2 in vitro.
Lin
Xiao-Cong
XC
Institute of Biochemistry and Molecular Biology, Guangdong Medical College, Zhanjiang, Guangdong, 524023, PR China.
Liu
Xin-Guang
XG
Chen
Xiao-Wen
XW
Chen
Wei-Zhu
WZ
Liang
Nian-Ci
NC
D047390:Casein Kinase II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D044950:Flavanones / Q000302:isolation & purification / Q000494:pharmacology*; D020035:Holoenzymes / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010946:Plants, Medicinal / Q000737:chemistry; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D031364:Scutellaria baicalensis / Q000737:chemistry
D004791:Enzyme Inhibitors; D044950:Flavanones; D020035:Holoenzymes; D011994:Recombinant Proteins; C006680:baicalein; D047390:Casein Kinase II