Endogenous cystinyl aminopeptidase in Chinese hamster ovary cells: characterization by [125I]Ang IV binding and catalytic activity

Involvement of insulin-regulated aminopeptidase in the effects of the renin–angiotensin fragment angiotensin IV: a review

“…In contrast, these substances are not required for the enzyme activity assay. Whereas highaffinity binding of [ 125 I]-Ang IV can only be detected with the apo-enzyme, inhibition of enzyme activity occurs to the native enzyme [182].…”

Assessment of biological activity of novel peptide analogues of angiotensin IV

“…The endogenous angiotensins Ang IV, and to a lesser extent angiotensin III, were able to inhibit the aminopeptidase activity of the brain homogenate ( P = 0.003 and 0.002, respectively, Friedman's test) (Figure 2); angiotensin II was without significant effect at the concentrations studied. The fact that Ang IV was able to inhibit the activity by approximately 60% at a concentration of 10 µ m indicates that IRAP probably accounts for the majority of the aminopeptidase activity; Ang IV is known to selectively inhibit IRAP with an IC 50 (inhibitory concentration 50%: concentration required to reduce the response by 50%) of approximately 1 µ m [15] . Of the synthetic peptides, [des‐Val 1 ]‐angiotensin IV, Ac‐angiotensin IV‐NH 2 , angiotensin IV‐NH 2 and [des‐His 4 ]‐angiotensin IV all inhibited IRAP to the same extent as Ang IV at similar concentrations ( P = 0.014; 0.002; 0.002 and 0.002, respectively, Friedman's test).…”

“…To determine aminopeptidase activity and the inhibitory effects of Ang IV, a method based on the cleavage of l ‐leucine‐ p ‐nitroanilide into l ‐leucine and p ‐nitroaniline was employed [14] . p ‐Nitroaniline shows a characteristic absorption at 405 nm upon cleavage by aminopeptidases [15] . Male C57BL/6 mice, all bred and raised in‐house, were sacrificed and whole brains removed and immediately placed in ice‐cold extraction buffer (50 m m Tris, 0.25 m sucrose, 140 m m NaCl pH 7.5).…”

Blood pressure and renal hemodynamic effects of angiotensin fragments

“…In contrast, systemic and intrarenal administration of Ang IV reduced RBF in rats when measured using pulsed Doppler flow probes placed around the renal artery, and this response was prevented by AT 1 receptor blockade. 44,131,132 Infusion of LVV-H7, a more stable ligand with a high affinity (K i B73 nM) for the AT 4 receptor, but no affinity for AT 1 receptors, 133 failed to alter RBF. 132 One study in anesthetized rats reported that intrarenal Ang IV produced an AT 1 receptordependent biphasic response with an immediate dose-dependent vasoconstriction, followed by a prolonged vasodilation.…”