title: Deoxyguanosine kinase from human placenta.
abstract: Deoxyguanosine kinase (ATP:deoxyguanosine 5'-phosphotransferase) has been purified up to a specific activity of 10.3 nmol/min per mg protein from human placenta. The enzyme appears to have a molecular weight of 58 000 from the results of Sephadex G-75 gel filtration. The enzyme catalyzed phosphorylation of deoxyguanosine and deoxyadenosine, but deoxycytidine was not phosphorylated. An apparent Km value for deoxyguanosine was 2.5 micro M. When ATP was used as a phosphate donor, the pH optimum was at pH 6.0, but the optimum was shifted to pH 6.8 by the addition of dTTP. At physiological pH, the activity was stimulated 3-4-fold by dTTP. dTTP was also an effective phosphate donor, but using dTTP as a phosphate donor, a broad pH optimum of 7.0 was observed. Two Km values of 0.13 and 2.2 mM were obtained for both MgATP2- and MgdTTP2-. The activity was strongly inhibited by dGTP and dGDP; 50% inhibition by 1.0 micro M dGTP and 2.1 micro M dGDP, respectively. The enzyme required the presence o Mg2+ or Mn2+.
mesh_terms: D002413:Cations, Divalent; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013379:Substrate Specificity
chemical_list: D002413:Cations, Divalent; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C019165:deoxyguanosine kinase