Structure-activity relationships of adenosine deaminase inhibitors

Adenosine deaminase (ADA) is an important catabolic enzyme which converts a denosine and deoxyadenosine to inosine and deoxyinosine, respectively. ADA exists in two different isoenzymes, namely ADA1 and ADA2, whose balance in monocytes-macrophages seems to guarantee the homeostasis of adenine nucleos ides. Modifications of the purine moiety or/and substitution of the sugar m oiety of adenosine with aliphatic chains led to derivatives which are good ADA inhibitors.