Open AccessCharacterization of DNA Kinase from Calf Thymus
Author(s) -
TAMURA Sanae,
TERAOKA Hirobumi,
TSUKADA Kinji
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb06222.x
Subject(s) - sephadex , sedimentation coefficient , enzyme , stokes radius , size exclusion chromatography , chemistry , microbiology and biotechnology , dna , biochemistry , gel electrophoresis , electrophoresis , pyrophosphate , polyacrylamide gel electrophoresis , molecular mass , enzyme assay , chromatography , kinase , biology
DNA kinase has been purified to homogeneity from calf thymus. The purified enzyme, with a specific activity of 16.7 units/mg protein at 25° C, exhibited a sharp pH/activity curve with a pH optimum at 5.5 and low activity at alkaline pH. The molecular weight of the enzyme was estimated by dodecylsulfate/polyacrylamide gel electrophoresis to be 5.4 × 10 4 . The enzyme has a sedimentation coefficient of 4.0 S. An apparent molecular weight of 5.6 × 10 4 and a Stokes' radius of 3.3 nm were estimated by gel‐filtration on Sephadex G‐100. The enzyme phosphorylates neither yeast RNA nor poly(A) instead of DNA. Compared with rat liver DNA kinase, calf thymus DNA kinase is relatively resistant to the inhibition by sulfate ( K i = 7 mM) and pyrophosphate ( K i = 5 mM). The enzyme activity is markedly stimulated by polyamines at the sub‐optimal concentration of Mg 2+ but not by monovalent cations.