Cory A H, Shibley I A, Chalovich J M, Cory J G
Department of Biochemistry, East Carolina University School of Medicine, Greenville, North Carolina 27858.
J Biol Chem. 1993 Jan 5;268(1):405-9.
A mouse leukemia L1210 cell line was selected for resistance to deoxyguanosine. The deoxyguanosine-resistant cells (dGuo-R) were 126-fold less sensitive to deoxyguanosine than the wild-type cells. The IC50 values for araC and araG were increased, but only 10-12-fold in the dGuo-R cells when compared with the wild-type cells. The dGuo-R cell line showed an increased level of resistance to 2-fluoro-2'-deoxyadenosine and 2-fluoroadenine arabinoside (11-14-fold), but essentially no increase in resistance to deoxyadenosine or adenine arabinoside. Deoxyribonucleoside kinase activity was decreased only slightly (19%) when deoxycytidine was utilized as substrate; when cytosine arabinoside or deoxyguanosine was used as the substrate, the kinase activity in the extracts from the dGuo-R cells was only 10% of the enzyme activity in the extracts from the wild-type cells. The determination of the kinetic parameters, Km and Vmax, indicated that there were marked decreases in the Vmax values for deoxyguanosine and cytosine arabinoside as substrates, but not for deoxycytidine as substrate; the Km values for deoxycytidine and cytosine arabinoside were increased in the extracts from the dGuo-R cells. By use of high-performance liquid chromatography, the kinase activities in the extracts from the wild-type and resistant cells could be resolved. There was the specific loss of kinase activity toward cytosine arabinoside and deoxyguanosine as substrates. These data indicate that the dGuo-R cells have decreased levels of a specific deoxyribonucleoside kinase activity.
选择一株对脱氧鸟苷具有抗性的小鼠白血病L1210细胞系。与野生型细胞相比，抗脱氧鸟苷细胞（dGuo-R）对脱氧鸟苷的敏感性低126倍。阿糖胞苷（araC）和阿糖鸟苷（araG）的IC50值升高，但与野生型细胞相比，dGuo-R细胞中的IC50值仅升高10 - 12倍。dGuo-R细胞系对2-氟-2'-脱氧腺苷和2-氟阿糖腺苷的抗性水平升高（11 - 14倍），但对脱氧腺苷或阿糖腺苷的抗性基本未增加。当以脱氧胞苷为底物时，脱氧核糖核苷激酶活性仅略有降低（19%）；当以阿糖胞苷或脱氧鸟苷为底物时，dGuo-R细胞提取物中的激酶活性仅为野生型细胞提取物中酶活性的10%。动力学参数Km和Vmax的测定表明，以脱氧鸟苷和阿糖胞苷为底物时Vmax值显著降低，但以脱氧胞苷为底物时未降低；dGuo-R细胞提取物中脱氧胞苷和阿糖胞苷的Km值升高。通过高效液相色谱法，可以分辨野生型和抗性细胞提取物中的激酶活性。存在以阿糖胞苷和脱氧鸟苷为底物的激酶活性特异性丧失。这些数据表明，dGuo-R细胞中特定脱氧核糖核苷激酶活性水平降低。
