title: Purification and characterization of thymidine kinase from regenerating rat liver.
abstract: Thymidine kinase (EC 2.7.1.21) from regenerating rat liver has been purified 70,000-fold to apparent homogeneity by affinity chromatography. Molecular weight of the native enzyme was found to be about 54,000, as determined by gel filtration. Electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate yielded a single band with a molecular weight of 26,000, suggesting that thymidine kinase is a dimer of very similar or identical subunits. The Michaelis constant for thymidine is 2.2 microM. ATP acts as a sigmoidal substrate with a 'Km' of 0.2 mM. Reaction kinetics and product inhibition studies reveal the enzymatic mechanism to be sequential.
authors.affiliation: Department of Food Science and Nutrition, Nara Women's University, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Tsukamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: M
authors.initials: M
authors.lastname: Miyoshi
authors.forename: S
authors.initials: S
authors.lastname: Kojo
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D007700:Kinetics; D008099:Liver / Q000201:enzymology* / Q000502:physiology; D008115:Liver Regeneration; D008297:Male; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity; D013937:Thymidine Kinase / Q000302:isolation & purification* / Q000378:metabolism*; D013938:Thymidine Monophosphate / Q000494:pharmacology
chemical_list: D013938:Thymidine Monophosphate; D000244:Adenosine Diphosphate; D013937:Thymidine Kinase