 A 2007 paper that described a series of studies by a team led by Seiji Negoro of the University of Hyogo, Japan, suggested that just two amino-acid alterations, i.e.G181D (from Gly181 (EII′-original enzyme ) to Asp (6-aminohexanoate-dimer hydrolase (EII) )) and H266N (from His266 (EII′)to Asn (EII)), confer the Ald-hydrolytic activity to the level of the parental EII enzyme10.These results suggest that the EII has evolved by gene duplication followed by base substitution from its ancestral gene.