This domain corresponds to an amidase function. Many of these proteins are involved in cell wall metabolism of bacteria. This domain is found at the N-terminus of Escherichia coli gss, where it functions as a glutathionylspermidine amidase EC:126.96.36.199. This domain is found to be the catalytic domain of PlyCA. CHAP is the amidase domain of bifunctional Escherichia coli glutathionylspermidine synthetase/amidase, and it catalyzes the hydrolysis of Gsp (glutathionylspermidine) into glutathione and spermidine.