title: Kinetics of 5-aza-2'-deoxycytidine phosphorylation in mouse spleen and L1210 leukemic cell extracts.
abstract: Out of different nucleosides and deoxynucleosides testes for their ability to block the phosphorylation of labeled 5-aza-2'-deoxycytidine in the presence of ATP and the cell-free extract from mouse spleen only deoxycytidine and cytosine arabinoside depressed the reaction significantly. With the same system the phosphate donor specificity for 5-aza-2'-deoxycytidine and deoxycytidine was determined. All of the 5'-triphosphates used were less efficient donors with respect to the analogue than to the natural substrate. The apparent Michaelis constants for the phosphorylation of 5-aza-2'-deoxycytidine and deoxycytidine were 2.9 and 2.5 x 10(-5) M, respectively. Using the extract from L1210 leukemic cells the Km constant for 5-aza-2'-deoxycytidine was 6.4 x 10(-5) M and that for deoxycytidine 2.7 x 10(-5) M. The Ki constants with the spleen extract were 1.2 x 10(-3) M for 5-aza-2'-deoxycytidine and 5.8 x 10(-6) M for deoxycytidine. Both compounds acted as competitive inhibitors of one another.
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism; D001667:Binding, Competitive; D002474:Cell-Free System; D000077209:Decitabine; D003842:Deoxycytidine Kinase / Q000378:metabolism; D003853:Deoxyribonucleosides / Q000494:pharmacology; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism*; D051379:Mice; D009705:Nucleosides / Q000494:pharmacology; D010766:Phosphorylation; D013154:Spleen / Q000378:metabolism*
chemical_list: D003853:Deoxyribonucleosides; D009705:Nucleosides; D000077209:Decitabine; D003842:Deoxycytidine Kinase; D001374:Azacitidine