Molecular Classification
Enzyme, Hydrolase
Other Names
Cytosine aminohydrolase
Disease Roles
Cancer

Cytosine Deaminase Overview

Cytosine deaminase (CD) is an enzyme that catalyzes the hydrolytic deamination of cytosine to uracil. Its key role in cancer therapy lies in its ability to convert the non-toxic prodrug 5-fluorocytosine (5-FC) into the cytotoxic chemotherapeutic agent 5-fluorouracil (5-FU) specifically within tumor cells when used in gene-directed enzyme prodrug therapy (GDEPT). CD is found in bacteria and fungi, but not in mammalian cells, allowing for targeted activation of 5-FU in tumors expressing the CD gene. The enzyme requires a zinc ion for its catalytic activity.

Mechanism of Action

Converts 5-Fluorocytosine to 5-Fluorouracil, leading to antimetabolite activity and cell death.

Biological Functions

Pyrimidine salvage pathway
Deamination of cytosine
Prodrug activation

Disease Associations

Cancer

Safety Considerations

  • Potential for off-target effects if cytosine deaminase is not selectively expressed in tumor cells.
  • Systemic toxicity of 5-Fluorouracil if conversion is not localized.

Interacting Drugs

5-Fluorocytosine (5-FC)
5-Fluorouracil (5-FU)