1. The liberation of ammonia from adenosine 5′-phosphate (AMP) and adenosine and the release of inorganic phosphate from AMP were investigated in homogenates of bovine and human parotid glands.
2. Adenosine phosphate deaminase (AMP deaminase) was purified from bovine and human parotid glands. The enzyme preparations obtained were free from adenosine deaminase and 5′-nucleotidase activities.
3. AMP incubated with human parotid gland homogenate produced inosine 5′-phosphate, adenosine, inosine and ammonia. The amount of ammonia accumulating in the incubation mixture was equal to the sum of inosine 5′-phosphate plus inosine.
4. These results demonstrate the presence in human parotid of AMP deaminase and adenosine deaminase.