Mechanism of inhibition of human renin by monoclonal antibodies.

Abstract

SUMMARY The mechanism by which monoclonal antibodies directed against human renin (R3-36-16 and R3-47-10) inhibit renin activity was investigated using various substrates. Both antibodies acted as potent inhibitors of human renin activity when human angiotensinogen was used as a substrate. However, their effects differed clearly in the presence of synthetic tetradecapeptide. When low concentrations of tetradecapeptide were used as substrate, renin activity was only partially inhibited by R3-47-10, whereas it was stimulated by R3-36-16. At higher synthetic substrate concentrations, both antibodies stimulated angiotensin I production. This effect was independent of the pH. Both antibodies exerted their effects in the presence of CGP 29287, a peptidic transition-state competitive renin inhibitor, indicating that their binding sites differed from that of CGP 29287. In combination, the stimulatory effect of R3-36-16 was not blocked by R3-47-10, but the inhibition produced by R3-47-10 was reversed by R3-36-16. Both antibodies may prevent the large natural substrate angiotensinogen from entering the enzymatic cleft by steric hindrance. At a low substrate concentration, R3-47-10 may also partially hinder the access of synthetic tetradecapeptide into the active cleft by steric hindrance. In contrast, the stimulating effect of both antibodies may be due to a conformational change in the renin molecule, allowing an increased access of tetradecapeptide or a more rapid release of the product from the enzymatic cleft. (Hypertension 11: 209-216, 1988

Antihypertensive effect of a fixed-dose combination of losartan /hydrochlorothiazide in patients with uncontrolled hypertension: a multicenter study

“…We followed all American Heart Association Recommendations published in 1988 [8, 10] including using a 47 × 13 cm cuff and 24 × 13 cm bladder to avoid cuff hypertension. The cuff was strictly positioned 2 cm above the antecubital crease to obtain a similarly leveled complete compression of the brachial artery.…”

Characterization of a monoclonal antibody specific for human active renin.

“…These data suggest that Rl-20-5 is specific for the active site of renin. We have shown previously 20 that R3-36-16 induced an enhanced formation of Ang I from the reaction of renin with the synthetic substrate TDP. This effect was inhibited by CGP 29287.…”

“…Kinetic studies showed that Rl-20-5 is a competitive inhibitor similar to the peptidic transition state analogue CGP 29287 20 as analyzed using the MichaelisMenten equation or constraining the data with the ALLFIT program (Table 2, Figure 2). The maximum rate (VMJ) remained unchanged, whereas the Michaelis constant (K m ) increased threefold to fourfold, respectively.…”

“…Our study demonstrates that the monoclonal antibody Rl-20-5 selectively binds human active renin but not prorenin. In contrast to R3-36-16 and R3-47-10, which noncompetitively stimulate or inhibit the production of Ang I from TDP-renin substrate, 20 Rl-20-5 is a competitive inhibitor of renin similar to a peptidic transition state analogue, CGP 29287. Both of these competitive inhibitors combine with renin in a manner that prevents substrate binding.…”

Alterations in immunodominance of Streptococcus mutans AgI/II: Lessons learned from immunomodulatory antibodies

“…Binding of an antibody to its cognate antigen can induce a conformational change in that antigen [51–67]. Importantly, these conformational changes can lead to exposure of functional subdominant or neoepitopes [54, 60, 65, 68–87], and such determinants can represent important targets of functional or neutralizing antibodies [62, 68, 88–97]. This is most evident in viral systems in which the availability of well-resolved crystal structures has outpaced that of bacterial molecules.…”