Coprecipitation of active uridine kinase and phosphomonoesterase from rat kidney by Zn2+-ions. III. Enzymes relevant to cancer chemotherapy.

Partially purified enzyme fraction from rat kidney possessing high uridine kinase and phosphomonoesterase activity was insolubilized by means of zinc precipitation without substantial loss of the activity. While uridine kinase in a soluble and Zn-precipitated form was inhibited by low concentrations (0.5-1.0 mM) of Zn2+-ions, phosphomonoesterase was fully active. In contrast to the soluble fraction, the two enzymes in zinc-precipitated and lyophilized preparations were stable on heating at 100 degrees C. Metal complexed proteins catalyze the dephosphorylation of 5'-UMP, 6-AzaUMP as well as of 2'(3')-UMP or 2,4-dinitrophenyl phosphate indicating thus the presence of several phosphomonoesterases in the complex.