Cytosine deaminase (CD) catalyses the deamination of cytosine, producing uracil. This enzyme is present in prokaryotes and fungi (but not multicellular eukaryotes) and is an important member of the pyrimidine salvage pathway in those organisms. The enzyme is of widespread interest both for antimicrobial drug design and for gene therapy applications against tumours.
Defined by 4 residues: HIS:A-102GLU:A-104CYS:A-129CYS:A-132