Uridine--cytidine kinase from foetal and adult rat liver. Purification and study of some properties.

Partial purification of uridine--cytidine kinase (EC 2.7.1.48) from foetal rat liver by chromatography on DEAE-cellulose gives two active fractions. The first in order of elution was identified as a form specific for foetal liver. It was purified 300-fold. The second fraction was common to foetal, and adult rat liver and spleen and was purified 20-fold. The foetal fraction of the enzyme was found to be heat-sensitive and protected against inactivation by PO34- anions. The two isolated forms have different apparent Km for uridine, respectively 410 muM for the foetal form and 52 muM for the adult form.