Presence and Properties of Cytidine Deaminase in Free living Ciliata Tetrahymena pyriformis

The present investigation indicated the presence and properties of cytidine deaminase (EC.3.5.4.5) activity in the extract of the free living ciliata Tetrahymena pyriformis.
The optimum conditions for the enzyme activity were determined.Maximum enzyme activity was obtained in a reaction mixture of (300)M of Tris-HCl buffer at pH (7.4) containing (3) mM of cytidine as a substrate, (250)g protein as a source of the enzyme, and an incubation period of (12) min. at (35)C.
Under the optimum conditions,the specific activity was found to be(32.240.91)M of cytidine deaminated per min per mg protein in the supernatant of Tetrahymena pyriformis extracts.The Results also indicated that cytidine monophosphate (CMP) might be used as alternative substrate for the enzyme under investigation .