Biological Properties of Angiotensin-Converting Enzyme Inhibitor Derived from Tuna Muscle

抄録

A novel inhibitor of angiotensin-converting enzyme (ACE) derived from tuna muscle, Pro-Thr-His-Ile-Lys-Trp-Gly-Asp (tuna AI), was chemically synthesized, and its biological properties were investigated. Synthetic tuna AI was found to be chemically and biologically indistinguishable from the native one. Tuna AI inhibited rabbit lung ACE non-competitively with K_i values of 1.7 and 5.7μM with substrates, hippuryl-L-histidyl-L-leucine and angiotensin I, respectively. This peptide (5.3μM) also doubled the effect of bradykinin in the contraction of isolated guinea pig ileum. The peptide did not show zinc chelating activity and carboxypeptidase A inhibitory activity. Thus, tuna AI was found to be a unique ACE inhibitory peptide with non-competitive manner, differing from many naturally occurring peptide ACE-inhibitors.