In enzymology, a blasticidin-S deaminase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are blasticidin S and H<sub>2</sub>O, whereas its two products are deaminohydroxyblasticidin S and NH<sub>3</sub>.
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 blasticidin-S aminohydrolase.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .