Design of rat renin inhibitory peptides

Abstract

Because several well-studied strains of rats manifest spontaneous hypertension, we set out to design a renin inhibitor suitable for use in this species. On the basis of the sequence of the renin substrate, a series of substrate analogue inhibitory peptides were synthesized by systematically modifying the P5, P3, P2, P1P1', P2', P3', and P4' positions. In assays against rat plasma renin, we found that modifications at the C-terminal segment have a marked influence on potency, and that a secondary butyl side chain at the P2' position is important for obtaining optimal activity. The structure at the P3' position, however, could vary considerably without significant effect. The steric effect of the P2 position was important; there an isopropyl side chain provided optimal binding between the inhibitor and the enzyme. At the P3 and P5 positions, potency appeared to depend on aromatic side chains. The effects at the P1P1' position of the transition-state residue (3S,4S)-4-amino-3-hydroxy -6-methylheptanoic acid (statine) and its congeners (3S,4S)-4-amino-3-hydroxy-5-phenylpentanoic acid (AHPPA) and (3S,4S)-4-amino-3-hydroxy-5-cyclohexylpentanoic acid (ACHPA) were found to depend on the sequence of the C-terminal segment. For peptides with an unfavorable C-terminal segment (-Ile-Phe-NH2), AHPPA and ACHPA resulted in a surprising retention of potency. For peptides with a favorable C-terminal segment (-Leu-Phe-NH2), the effect of AHPPA was mild, even though ACHPA still significantly enhanced potency. The hypotensive and plasma renin inhibitory effects of three of the analogues were then studied in anesthetized sodium-depleted rats. One of the compounds, acetyl-His-Pro-Phe-Val-Statine-Leu-Phe-NH2 (IC50 against rat plasma renin of 30 nM at pH 7.4), proved to be a potent hypotensive agent and a potentially useful probe for the study of the renin-angiotensin system in rats.

Design of potent substrate‐analogue inhibitors of canine renin

“…Peptide synthesis The peptides were synthesized, purified, and analyzed by methods reported previously (4,13). The Fmoc protecting group of the para-aniinophenglalanine residue was removed either by treating the peptidyl resin with 30% piperidine in D M F or by triturating an ethanol solution of the crude peptide with 1 N NaOH.…”

“…The renin inhibitory peptides were synthesized in a stepwise manner as described previously (4,13). The renin inhibitory peptides were synthesized in a stepwise manner as described previously (4,13).…”

“…The renin inhibitory potency of the peptides was determined as described (4,13). The blood samples were centrifuged at 4" to separate the plasma.…”

“…We have already described our synthesis and activity studies on rat renin inhibitors (4). We have already described our synthesis and activity studies on rat renin inhibitors (4).…”

Type 2 Bradykinin-Receptor Antagonism Does Not Modify Kinin or Angiotensin Peptide Levels

“…16 Briefly, trunk blood (2 to 3 mL) was rapidly collected in tubes that contained 0.5 mL inhibitor solution (1 mmol/L renin inhibitor acetyl-His-Pro-Phe-Val-Sta-Leu-Phe-NH 2 , 17 146 mol/L pepstatin, 50 mmol/L 1,10-phenanthroline, 125 mmol/L EDTA, 2 g/l neomycin sulfate, 2% dimethyl sulfoxide, and 2% ethanol in water) at 4°C. The blood was centrifuged, and the plasma (1 to 2 mL) was immediately extracted with Sep-Pak C 18 cartridges (Waters Chromatography Division).…”