Adenosine/AMP deaminase. Adenosine deaminases (ADAs) are present in pro- and eukaryotic organisms and catalyze the zinc dependent irreversible deamination of adenosine nucleosides to inosine nucleosides and ammonia. The eukaryotic AMP deaminase catalyzes a similar reaction leading to the hydrolytic removal of an amino group at the 6 position of the adenine nucleotide ring, a branch point in the adenylate catabolic pathway.