Abstract
Cytidine deaminase (EC 3.5.4.5) catalyzes the irreversible hydrolytic deamination of both cytidine and its nucleoside analogues including many antineoplastic agents. The enzyme has been purified from human spleen 2000-fold with respect to the crude extract. The procedure consists of heat treatment, anionic exchange on DEAE-52, hydrophobic interaction on TSK-Phenyl-5PW and an anionic exchange on Mono Q. The last two steps were performed using an FPLC system. The final enzyme preparation shows a microheterogeneity. The native molecular weight is about 50,000. Cytidine deaminase is strictly dependent on the presence of reducing agents for its activity. The enzyme displays linear kinetics. It shows the highest affinity for deoxycytidine among the various substrates tested. The enzyme is inhibited by the reaction products uridine and ammonia in a competitive fashion suggesting a rapid equilibrium random Uni-Bi kinetic mechanism. Furthermore, the enzyme is competitively inhibited by various compounds, such as 5, 6-dihydrouridine, deoxyuridine, thymidine, thymine riboside and deoxyadenosine.
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Cacciamani, T., Rosati, F., Vita, A. et al. 168 MOLECULAR AND KINETIC PROPERTIES OF CYTIDINE DEAMINASE FROM HUMAN SPLEEN. Pediatr Res 24, 139 (1988). https://doi.org/10.1203/00006450-198807000-00192
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DOI: https://doi.org/10.1203/00006450-198807000-00192