“…The tripeptides hippuryl-L-histidyl-L-leucine (van Platerink et al, 2007) and hippurylglycylglycine (Jafarian-Tehrani et al, 2000) are commonly employed as substrates for angiotensin converting enzyme (ACE; peptidyl-dipeptidase A; EC 3.4.15.1) and are hydrolyzed by dipeptidase activity leaving the stable HA. Circulating HAwill certainly be exposed to ACE since it is expressed mainly in lung, vascular endothelium and kidney (Femia et al, 2008). However, when HA is exposed to the gastrointestinal tract, it may not be stable.…”