In enzymology, a S-adenosylhomocysteine deaminase () is an enzyme that catalyzes the chemical reaction S-adenosyl-L-homocysteine + H2O S-inosyl-L-homocysteine + NH3 Thus, the two substrates of this enzyme are S-adenosyl-L-homocysteine and H2O, whereas its two products are S-inosyl-L-homocysteine 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 S-adenosyl-L-homocysteine aminohydrolase. This enzyme is also called adenosylhomocysteine deaminase. References EC 3.5.4 Enzymes of unknown structure