Catalyzes the hydrolysis of short-chain aliphatic amides to their corresponding organic acids with release of ammonia. Hydrolyzes propionamide, acetamide and acrylamide, but has no activity with formamide or urea. The natural substrates of AmiE in its gastric environment are not known. Probably functions to ensure nitrogen supply to the bacteria. Also exhibits in vitro acyl transferase activity, transferring the acyl moiety of short-chain amides to hydroxylamine to form hydroxamates. The highest level of acyl transfer activity is observed with acetamide. a monocarboxylic acid amide + H2O = a monocarboxylate + NH4(+) Inhibited by iodoacetate. Optimum pH is 7. Optimum temperature is 55 degrees Celsius. Homotetramer. Repressed by iron via the binding of the Fur protein to the amiE promoter. Asp-167 is probably not involved in the catalytic mechanism, but is probably involved instead in maintenance of the structural integrity of the amidase. Expression of the amiE gene is stimulated in a mutant deficient in urease activity, suggesting that production of this enzyme is regulated to maintain intracellular nitrogen balance in H.pylori. Belongs to the carbon-nitrogen hydrolase superfamily. Aliphatic amidase family.