Al-Mudhaffar S A, Saadalla V
Biochem Exp Biol. 1978;14(4):347-57.
The kinetic properties of 5'-Nucleotidase were investigated in untreated patients with liver cirrhosis at 37 degrees C. Mg+2 and Mn+2 were found to activate both normal and liver cirrhotic 5'-Nucleotidase, but Nickel inhibited the enzyme in both systems competitively. Both ATP and adenosine act as inhibitors to 5'-Nucleotidase. The inhibitory constant for ATP was different in normal and liver cirrhotic individuals, 0.1 +/- 0.03 for normal and 0.225 +/- 0.02 for liver cirrhosis. In our investigation, ATP was found to be a competitive inhibitor of 5'-Nucleotidase which compete the substrate (A-5'-MP) for the active site. Inhibition of 5'-Nucleotidase by adenosine is of non-competitive type, for both normal and liver cirrhotic sera. It was observed that both serum 5'-Nucleotidase exhibited pH dependent characteristics; in that there was an optimum substrate concentration at each pH value and the plot of pKm versus pH shows great dependency of km on pH.
在37摄氏度下，对未经治疗的肝硬化患者的5'-核苷酸酶的动力学特性进行了研究。发现Mg+2和Mn+2均可激活正常和肝硬化患者的5'-核苷酸酶，但镍在两个系统中均竞争性抑制该酶。ATP和腺苷均对5'-核苷酸酶起抑制作用。正常人和肝硬化患者中ATP的抑制常数不同，正常人中为0.1±0.03，肝硬化患者中为0.225±0.02。在我们的研究中，发现ATP是5'-核苷酸酶的竞争性抑制剂，它与底物（A-5'-MP）竞争活性位点。腺苷对5'-核苷酸酶的抑制作用在正常血清和肝硬化血清中均为非竞争性类型。观察到两种血清5'-核苷酸酶均表现出pH依赖性特征；即在每个pH值处都有一个最佳底物浓度，并且pKm与pH的关系图显示Km对pH有很大依赖性。
