Extracellular purine-specific hydrolase present in the apoplastic fluid involved in the degradation of extracellular nucleosides, including inosine and adenosine, and which may participate in wound and pathogen responses (e.g. Botrytis cinerea). a purine D-ribonucleoside + H2O = a purine nucleobase + D-ribose H2O + inosine = D-ribose + hypoxanthine adenosine + H2O = adenine + D-ribose Optimum pH is 4.8. Present in the apoplastic fluid. By jasmonic acid (JA) and wounding. Impaired hydrolysis of inosine and adenosine by apoplastic fluid leading to an increased sensitivity to 2-chloroadenosine (PubMed:21235647). The isolated apoplastic sap extracted from the double mutant missing both NSH3 and ENT3 lacks the ability to catalyze the conversion of inosine in hypoxanthine; this double mutant is unable to grow on medium containing inosine as sole nitrogen source, in addition plants are more sensitive to the necrotrophic fungus Botrytis cinerea BMM but are resistant to the cytotoxic adenosine analog 2-chloro-adenosine (CADO) and to 5-fluoro-uridine (PubMed:26779190). Belongs to the IUNH family.