What is the function and mechanism of Adenosine aminohydrolase(EC 3.5.4.4)?

Adenosine aminohydrolase(EC 3.5.4.4) is a purine catabolic enzyme ubiquitous in mammalian tissue which catalyzes deamination of both adenosine and 2'-deoxyadenosine to inosine and 2'-deoxyinosine respectively. The proposed mechanism for adenosine deaminase (ADA)-catalyzed deamination is stereospecific addition-elimination via tetrahedral intermediate. By either mechanism, Zn2+ as a strong electrophile activates a water molecule, which is deprotonated by the basic Asp295 to form the attacking hydroxide. His238 orients the water molecule and stabilizes the charge of the attacking hydroxide. Glu217 is protonated to donate a proton to N1 of the substrate.

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