Evidence for two binding sites on membrane-bound angiotensin-converting enzymes (ACE) for exogenous inhibitors except...

It was possible to assess that ACE inhibitors bound to two different sites on the enzymes which consist in two homologous domains. Accordingly, it was also shown that testis ACE which consists in a single domain exhibits only one site for inhibitors. The common binding site of both enzymes contains Zn2+, bears the enzymatic activity, is less sensitive to added Zn2+ and Cl- and has a lower affinity for inhibitors than the first one, found only in duplicated domain enzymes and highly sensitive to the effect of ions.