Catalyzes the hydrolytic deamination of dCMP to yield dUMP, the nucleotide substrate for thymidylate synthetase. dCMP + H(+) + H2O = dUMP + NH4(+) Allosteric enzyme whose activity is greatly influenced by the end products of its metabolic pathway, dCTP and dTTP. Present with 1510 molecules/cell in log phase SD medium. Belongs to the cytidine and deoxycytidylate deaminase family.