Purification and Properties of Pyrimidine Nucleoside Monophosphate Kinase from Baker's Yeast

Abstract

Pyrimidine nucleoside monophosphate kinase was purified from baker's yeast to 280-fold. The molecular weight of the enzyme was calculated to be 26, 000 by gel filtration. With ATP as a phosphate donor, UMP was the most active phosphate acceptor. Besides UMP, the kinase also phosphorylated CMP, dCMP and dUMP. Km values for UMP, CMP, dCMP and dUMP were 0.052, 0.071, 0.54 and 8.5mM, respectively. The kinase was activated by preincubation with dithiothreitol. The extent of the activation depended on the concentration of dithiothreitol and incubation time. HgCl₂, p-CMB and N-ethylmaleimide inhibited this enzyme.