Isoenzymes of GMP Kinase from L1210 Cells: Isolation and Characterization
Guanylate kinase from a mouse leukemic L1210 cells has been purified nearly to homogeneity for the first time. It consists of five isoenzymes with p I 5.95, 5.50, 5.08, 4.83 and 4.51, respectively. The native enzyme is a monomer with a relative molecular mass 25 000. The kinetic constants K m , V max and k cat / K m of isoenzymes were estimated. The purified GMP kinase is absolutely specific to GMP and/or dGMP as phosphate acceptor but has a broad specificity to nucleoside 5'-triphosphates as phosphate donors.