A schematic representation of the structure of truncated, deglycosylated human gACE in a complex with the inhibitor lisinopril . The gACE molecule can be divided into two halves, subdomains I (light gray) and II (dark gray), that enclose the substrate-binding site. The active-site zinc atom is shown coordinated to lisinopril (in stick representation). Two bound chloride ions are designated Cl1 and Cl2. N, amino terminus; C, carboxyl terminus.