Rational truncation, mutation, and halogenation of bradykinin neuropeptides as potent ACEII inhibitors by integrating molecular dynamics simulations, quantum mechanics calculations, and in vitro assays

Abstract

Human angiotensin‐converting enzyme‐ii (ACEII) is involved in the brain renin‐angiotensin system and plays a key role in angiotensin metabolism and neural regulation. Here, we systematically investigated the intermolecular interaction of ACEII with its natural inhibitor bradykinin neuropeptide (BNP) at molecular level and found that the residue importance increases from peptide N‐ to C‐terminus; the four C‐terminal residues accumulatively account for ~70% total binding potency for BNP∆N to ACEII, which represent an N‐truncated tetrapeptide (BNP∆N) with comparable ACEII‐inhibitory activity with the full‐length BNP peptide. Mutagenesis analysis imparted that the mutation of BPPb∆N's two C‐terminal residues to phenylalanine (Phe) would largely impair its inhibitory activity, whereas such mutation on the two N‐terminal residues has only a moderate effect on the activity. The two N‐terminal Phe‐mutated tetrapeptides BNP∆N(I−2F) and BNP∆N(K−3F) were then used as templates and the ortho (o)‐, meta (m)‐, para (p)‐positions of the phenyl ring of their Phe residues were systematically substituted with different halogen types. The halogen substitution separately at the m‐position of BNP∆N(I−2F) Phe−2 residue and at the p‐position of BNP∆N(K−3F) Phe−3 residue can form a ternary halogen bonding system with ACEII His353/Lys368 residues and a binary bonding system with ACEII Glu403 residue, respectively. The [Br]Phe‐containing BNP∆N(I−2F‐mBr) and [I]Phe‐containing BNP∆N(K−3F‐pI) were determined to have high affinities for ACEII, which were improved considerably from their unsubstituted counterparts BNP∆N(I−2F) and BNP∆N(K−3F), respectively.

Machine annealing‐guided navigation of antihypertensive food peptide selectivity between human ACE N‐ and C‐domains in structurally interacting diversity space

“…The peptide binding affinities to ACE N-and C-domains were determined using fluorescence protocol referring to an experimental protocol modified from our previous works 53,54 with conditions corrected by a recent report. 55 The fluorescence was monitored as a function of increasing amounts of ACE domain proteins added to the labeled peptides in a buffer. Each assay was read three times and the values were averaged prior to analysis.…”