Nikolaev A Ia, Likhacheva N V, Burobin V A, Osipov E V
Biokhimiia. 1976;41(7):1279-84.
A dependence of rat liver urocaninase activity on the agents affecting the adenylate cyclase system was studied in vitro and in vivo. Urocaninase is considerably activated after the injection of glucagone, NaF, theophylline and 3',5'-AMP. Under conditions optimal for the protein kinase activity of phosphorylase the urocaninase of liver extracts was activated 7-fold on the average. The nezyme retains its activity after gel-filtration through Sephadex G-25 and is capable of inactivation in the presence of Mg2+ and of reactivation after addition of ATP and 3',5'-AMP. These data suggest a possibility of regulation of mammalian liver urocaninase activity by 3',5'-AMP-dependent phosphorylation of the enzyme. Derivatives of hypoxanthine (theophylline and caffeine) in concentration 10(-4) M activate urocaninase in liver extracts 2--3 and 1.5-fold respectively. The activation is probably not due to the 3',5'-AMP phosphodiesterase inhibition, since another phosphodiesterase inhibitor--papaverine--has no activating effect on urocaninase.
在体外和体内研究了大鼠肝脏尿刊酸酶活性对影响腺苷酸环化酶系统的试剂的依赖性。注射胰高血糖素、氟化钠、茶碱和3',5'-AMP后，尿刊酸酶被显著激活。在对磷酸化酶的蛋白激酶活性最适宜的条件下，肝脏提取物中的尿刊酸酶平均被激活7倍。该酶经Sephadex G-25凝胶过滤后仍保留其活性，并且在存在Mg2+时能够失活，在添加ATP和3',5'-AMP后能够重新激活。这些数据表明，3',5'-AMP依赖性的酶磷酸化可能调节哺乳动物肝脏尿刊酸酶的活性。浓度为10(-4) M的次黄嘌呤衍生物（茶碱和咖啡因）分别使肝脏提取物中的尿刊酸酶激活2 - 3倍和1.5倍。这种激活可能不是由于3',5'-AMP磷酸二酯酶的抑制，因为另一种磷酸二酯酶抑制剂——罂粟碱——对尿刊酸酶没有激活作用。
