Is an aliphatic amidase with a restricted substrate specificity, as it only hydrolyzes formamide. Probably involved in the nitrogen metabolism of H.pylori. formamide + H2O = formate + NH4(+) Inhibited by iodoacetate. Appears to be regulated by the fur protein, but this effect is not mediated at the transcriptional level. Optimum pH is 6. Optimum temperature is 45 degrees Celsius. Homotetramer. Unlike the other amidase AmiE, expression of amiF is not repressed by iron. Asp-168 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 amiF gene is stimulated in a mutant deficient in arginase 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.