Hathaway G M, Lubben T H, Traugh J A
J Biol Chem. 1980 Sep 10;255(17):8038-41.
Casein kinase II, a cyclic nucleotide-independent protein kinase from rabbit reticulocytes, was shown to be inhibited by heparin. Heparin specifically inhibited the enzyme and had no effect on other protein kinases, including casein kinase I, the type I and II cAMP-dependent protein kinases, protease-activated kinase I, and the hemin-controlled repressor. Heparan sulfate was found to be 40-fold less effective than heparin towards casein kinase II; other acid mucopolysaccharides had little or no effect on the enzymatic activity. Steady state studies revealed that heparin acted as a competitive inhibitor with respect to the substrate, casein. A value of 20 ng/ml or about 1.4 nM was obtained for the apparent Ki. The inhibition was not reversed by ATP and varying the ATP and heparin concentrations in the assay only altered the maximum velocity.
酪蛋白激酶II是一种来自兔网织红细胞的不依赖环核苷酸的蛋白激酶，已证明它会被肝素抑制。肝素特异性地抑制该酶，对其他蛋白激酶没有影响，包括酪蛋白激酶I、I型和II型cAMP依赖性蛋白激酶、蛋白酶激活激酶I以及血红素控制阻遏物。发现硫酸乙酰肝素对酪蛋白激酶II的作用效果比肝素低40倍；其他酸性粘多糖对酶活性几乎没有影响。稳态研究表明，肝素对底物酪蛋白起竞争性抑制剂的作用。表观Ki值为20 ng/ml或约1.4 nM。ATP不能逆转这种抑制作用，并且在测定中改变ATP和肝素的浓度只会改变最大反应速度。
