This enzyme scavenges exogenous and endogenous cytidine and 2'-deoxycytidine for UMP synthesis. cytidine + H(+) + H2O = NH4(+) + uridine 2'-deoxycytidine + H(+) + H2O = 2'-deoxyuridine + NH4(+) Binds 1 zinc ion. Homodimer. Belongs to the cytidine and deoxycytidylate deaminase family.