Isoenzymes of GMP Kinase from L1210 Cells: Isolation and Characterization

Abstract

Guanylate kinase from a mouse leukemic L1210 cells has been purified nearly to homogeneity for the first time. It consists of five isoenzymes with pI 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 Km, Vmax and kcat/Km 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.