Cihák A
Hoppe Seylers Z Physiol Chem. 1976 Mar;357(3):345-50.
Partially purified calf brain uridine kinase precipitated by bivalent metal cations has been compared with the soluble enzyme fraction regarding its stability in the presence of inactivating factors. The freeze-dried preparations of uridine kinase precipitaated by Pb2+ or Zn2+ ions, althouth enzymatically highly active, are insoluble in aqueous solutions. The activity of metal-insolubilized enzymes disappears during their preincubation in acidic media or in the presence of silver ions. Also trypsin, chymotrypsin and cathepsin B1 caused decreases in enzyme activity. However, fractions which have been precipitated by metal ions and freeze-dried are stable at high temperatures, whereas the activity of soluble uridine kinase is completely lost. Both unheated metal-ion precipitated uridine kinase preparations and those heated at 100 degrees C are equally sensitive to the feedback inhibition by CTP.
已将由二价金属阳离子沉淀得到的部分纯化的小牛脑尿苷激酶，就其在失活因子存在下的稳定性与可溶性酶部分进行了比较。由Pb2+或Zn2+离子沉淀得到的尿苷激酶冻干制剂，虽然酶活性很高，但不溶于水溶液。金属不溶性酶在酸性介质中预孵育或在银离子存在下，其活性会消失。胰蛋白酶、胰凝乳蛋白酶和组织蛋白酶B1也会导致酶活性降低。然而，由金属离子沉淀并冻干的部分在高温下是稳定的，而可溶性尿苷激酶的活性则完全丧失。未加热的金属离子沉淀的尿苷激酶制剂和在100℃加热的制剂对CTP的反馈抑制同样敏感。
