FRACTIONATION OF THYMIDINE PHOSPHOKINASE, THYMIDINE 5′-MONOPHOSPHATE PHOSPHOKINASE AND THYMIDINE 5′-DIPHOSPHATE PHOSPHOKINASE IN EXTRACTS OF LANDSCHUTZ ASCITES-TUMOUR CELLS

Abstract

Extracts of Landschutz ascites-tumor cells have been fractionated by treatment with acid, alumina C, gel and Sephadex G-100 to yield purified preparations of thymidine phosphokinase, thymidine 5[image]-monophosphate phosphokinase and thymidine 5[image]-diphosphate phosphokinase. These results clearly demonstrate the existence in Landschutz ascites tumor of 3 phospho-kinases each of which catalyses one step in the reaction sequence thymidine [image] thymidine 5[image]-monophosphate [image] thymidine 5[image]-diphosphate [image] thymidine 5[image]-triphosphate. Though these results do not preclude the participation of other enzymes in the formation of thymidine 5[image]-tri-phosphate from thymidine by Landschutz ascites-tumor cells, they provide strong support for the view that thymidine 5[image]-diphosphate is an intermediate in the formation of thymidine-5[image]-triphosphate from thymidine 5[image]-monophosphate by this system.