Adenosine Deaminase (ADA) is an enzyme crucial for purine metabolism, the process of breaking down and recycling purine molecules. It is found in cells throughout the body, with the highest levels in lymphocytes, a type of white blood cell vital for the immune system.

Key Functions of ADA
The primary role of the ADA enzyme is to catalyze the irreversible deamination of:
Adenosine to inosine.
Deoxyadenosine to deoxyinosine.
This conversion is essential because a byproduct of DNA breakdown, deoxyadenosine, can be converted into deoxyadenosine triphosphate (dATP). High levels of dATP are toxic to cells, particularly to rapidly dividing lymphocytes, and can lead to early cell death. ADA helps eliminate this toxic buildup, thereby maintaining a healthy immune system.