KINETIC-STUDIES ON 2',2'-DIFLUORODEOXYCYTIDINE (GEMCITABINE) WITH PURIFIED HUMAN DEOXYCYTIDINE KINASE AND CYTIDINE DEAMINASE
KINETIC-STUDIES ON 2',2'-DIFLUORODEOXYCYTIDINE (GEMCITABINE) WITH PURIFIED HUMAN DEOXYCYTIDINE KINASE AND CYTIDINE DEAMINASE
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DOI：
10.1016/0006-2952(93)90444-2
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发表时间：
1993-05-05
影响因子：
5.8
通讯作者：
MOMPARLER, RL
中科院分区：
文献类型：
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作者：
BOUFFARD, DY;LALIBERTE, J;MOMPARLER, RL
脱氧胞苷激酶（dCK）对胞嘧啶类似物的磷酸化和胞苷脱氨酶（CDA）对胞嘧啶类似物的脱氨作用是这些药物活化和消除的两个重要过程。我们研究了2 '，2'-二氟脱氧胞苷（dFdC）使用纯化的酶从人类细胞的动力学参数。脱氧胞苷（CdR）和dFdC对dCK的K（m）值分别为1.5和4.6 μ M。还研究了脱氧胞苷5 '-三磷酸（dCTP）对dCK的反馈抑制。我们的研究结果表明，dCTP产生了更大的抑制dFdC的磷酸化比CdR与dCTP的浓度范围从1到25 μ M。dFdC是CDA的良好底物。用这种酶的动力学研究给出了CdR和dFdC的K（m）值分别为46.3和95.7 μ M。研究了CDA竞争性抑制剂对dFdC脱氨基反应的影响。二氮杂卓酮核苷是一个更有效的抑制剂比四氢尿苷使用CdR或dFdC作为底物。CDA抑制剂可用于癌症患者的临床试验，以增加dFdC的化疗效果。
Phosphorylation of cytosine analogs by deoxycytidine kinase (dCK) and deamination by cytidine deaminase (CDA) are two important processes in the activation and elimination of these drugs. We have investigated the kinetic parameters of 2',2'-difluorodeoxycytidine (dFdC) using purified enzymes from human cells. Deoxycytidine (CdR) and dFdC had K(m) values of 1.5 and 4.6 muM for dCK, respectively. Feedback inhibition of dCK by deoxycytidine 5'-triphosphate (dCTP) was also studied. Our results show that dCTP produced a greater inhibition of the phosphorylation of dFdC than CdR with concentrations of dCTP ranging from 1 to 25 muM. dFdC was a good substrate for CDA. Kinetic studies with this enzyme gave K(m) values for CdR and dFdC of 46.3 and 95.7 muM, respectively. The effect of competitive inhibitors of CDA on the deamination of dFdC was also investigated. Diazepinone riboside was a more potent inhibitor than tetrahydrouridine using either CdR or dFdC as the substrate. Inhibitors of CDA could be useful in clinical trials in patients with cancer to increase the chemotherapeutic effectiveness of dFdC.