adenine + H(+) + H2O = hypoxanthine + NH4(+) Optimum pH is 6.5-7.0. Optimum temperature is 60 degrees Celsius. Homodimer. Repressed by H-NS. Activated by insertion of a variety of IS elements into a region extending from -145 to +13 relative to the transcription start site. IS elements essentially eliminate the H-NS-mediated silencing, but also stimulate ade expression 2-3 fold independently of the H-NS protein. Ade is a cryptic gene in wild-type strains. The physiological conditions that lead to its activation are unknown. Belongs to the metallo-dependent hydrolases superfamily. Adenine deaminase family.