title: Thymidine kinase enzyme variants in Physarum polycephalum. In vitro interconversion of the enzyme variants.
abstract: Isoelectric focusing of plasmodial extracts of Physarum polycephalum demonstrated the presence of several multiple enzyme variants of thymidine kinase, which appear sequentially during the nuclear division cycle. Variants (A) + (A1) are the only enzyme variants found in the late G2-phase, whereas the variants (C) + (C1) are only present at the time of mitosis and S-phase (1, 2). Evidence is presented that multiple forms of thymidine kinase (A) + (A1) with high pI arise by dephosphorylation of a primary translation product with low pI (C and/or C1). The thymidine kinase fractions (A) + (A1) and (C) + (C1) + (c1) were separated and partially purified by DEAE-cellulose chromatography. The enzyme variants (C) + (C1) are converted in vitro by an endogenous enzymatic factor as well as by bacterial alkaline phosphatase into the variants (A) + (A1).
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D002413:Cations, Divalent; D002453:Cell Cycle; D014644:Genetic Variation; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000378:metabolism; D010804:Physarum / Q000201:enzymology*; D013937:Thymidine Kinase / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D007527:Isoenzymes; D013937:Thymidine Kinase; D009597:4-Nitrophenylphosphatase