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Nucleoside kinase activities of Chinese hamster ovary cells
Abstract:
Chinese hamster ovary (CHO) cells and appropriate drug-resistant mutants derived from them have been analyzed for nucleoside kinase activities relevant to the phosphorylation of adenosine, deoxyadenosine, deoxyguanosine and deoxycytidine and for resistance to a variety of nucleoside analogs. Fractionation of extracts by DEAE-cellulose chromatography revealed three major peaks of activity. Adenosine kinase (ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20), the first to elute from the column is responsible for the majority of the deoxyadenosine phosphorylation in cell extracts and, according to resistance data, appears to phosphorylate most adenosine analogs tested, including 9-beta-D-arabinosyladenine (ara-A). A deoxyguanosine kinase, the second enzyme to elute from the column, was responsible for the majority of deoxyguanosine and deoxyinosine phosphorylation in cell extracts. The function of this enzyme in cell metabolism is unclear. 2-Chlorodeoxyadenosine, on the other hand, appeared from resistance data to be phosphorylated, at least in part, by deoxycytidine kinase (ATP:deoxycytidine 5'-phosphotransferase, EC 2.7.1.74), which in cell extracts could also phosphorylate deoxyguanosine and deoxyadenosine, though much less efficiently than deoxycytidine.
Insights
Chinese hamster ovary (CHO) cells exhibit distinct nucleoside kinase activities essential for phosphorylating various nucleosides and analogs. Adenosine kinase, deoxyguanosine kinase, and deoxycytidine kinase play key roles in these processes.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Pharmacology
Background:
- Chinese hamster ovary (CHO) cells are widely used models for studying cellular metabolism and drug resistance.
- Nucleoside kinases are crucial enzymes involved in the activation and metabolism of nucleosides and their analogs.
Purpose of the Study:
- To characterize nucleoside kinase activities in CHO cells and their drug-resistant mutants.
- To elucidate the roles of specific kinases in the phosphorylation of adenosine, deoxyadenosine, deoxyguanosine, and deoxycytidine.
Main Methods:
- Fractionation of cell extracts using DEAE-cellulose chromatography.
- Analysis of enzyme activities and drug resistance profiles.
- Identification of key nucleoside kinases involved in nucleoside analog phosphorylation.
Main Results:
- Three major nucleoside kinase activities were identified: adenosine kinase, deoxyguanosine kinase, and deoxycytidine kinase.
- Adenosine kinase primarily phosphorylates deoxyadenosine and many adenosine analogs, including 9-beta-D-arabinosyladenine (ara-A).
- Deoxycytidine kinase partially phosphorylates 2-chlorodeoxyadenosine and can also phosphorylate deoxyguanosine and deoxyadenosine, albeit less efficiently.
Conclusions:
- Adenosine kinase is the primary enzyme for deoxyadenosine phosphorylation and analog activation in CHO cells.
- The specific roles of deoxyguanosine kinase and deoxycytidine kinase in cellular metabolism and drug response require further investigation.
- Understanding these kinase activities is vital for developing targeted nucleoside analog therapies.