In enzymology, a guanosine deaminase () is an enzyme that catalyzes the chemical reaction guanosine + H2O xanthosine + NH3 Thus, the two substrates of this enzyme are guanosine and H2O, whereas its two products are xanthosine and NH3. This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amidines. The systematic name of this enzyme class is guanosine aminohydrolase. This enzyme is also called guanosine aminase. References EC 3.5.4 Enzymes of unknown structure