Catalyzes the hydrolytic deamination of adenosine and 2-deoxyadenosine (By similarity). Plays an important role in purine metabolism and in adenosine homeostasis (By similarity). Modulates signaling by extracellular adenosine, and so contributes indirectly to cellular signaling events (By similarity). Acts as a positive regulator of T-cell coactivation, by binding DPP4 (By similarity). Its interaction with DPP4 regulates lymphocyte-epithelial cell adhesion (By similarity). Enhances dendritic cell immunogenicity by affecting dendritic cell costimulatory molecule expression and cytokines and chemokines secretion (PubMed:23240012). Enhances CD4+ T-cell differentiation and proliferation (By similarity). Acts as a positive modulator of adenosine receptors ADORA1 and ADORA2A, by enhancing their ligand affinity via conformational change (By similarity). Stimulates plasminogen activation (By similarity). Plays a role in male fertility (By similarity). Plays a protective role in early postimplantation embryonic development (By similarity). adenosine + H(+) + H2O = inosine + NH4(+) Binds 1 zinc ion per subunit. Interacts with DPP4 (via extracellular domain). Interacts with PLG (via Kringle 4 domain); the interaction stimulates PLG activation when in complex with DPP4. Colocalized with DPP4 at the cell surface. Expressed in gastrointestinal tissues (at protein level). Available under the name Adagen (Enzon). This is a PEG-conjugated form (pegademase). Used to treat patients with severe combined immunodeficiency diseases (SCID). Belongs to the metallo-dependent hydrolases superfamily. Adenosine and AMP deaminases family.