Catalyzes the deamination of adenosine into inosine. Is also able to deaminate adenine, but with considerably less efficiency. Is not active toward 6-chloroadenine. adenosine + H(+) + H2O = inosine + NH4(+) Binds 1 zinc ion per subunit. kcat is 1101 min(-1) and 0.47 min(-1) with adenosine and adenine as substrate, respectively. Optimum pH is about 7.5. Retains > 70% maximum activity at pH 9.0, but displays only 6% activity at pH 4.5. Optimum temperature is about 45 degrees Celsius. Belongs to the metallo-dependent hydrolases superfamily.