pe
pep-04813 v1 CC-BY-SA-4.0

Blood-pressure-lowering peptide (FRAHPFL)

A small protein fragment that blocks ACE, the enzyme that raises blood pressure; studied as a potential treatment for high blood pressure, experimental, not yet an approved drug.

statusbioassayed targetACE length7 aa refs1
angiotensin-converting-enzyme-ace-inhibitorsanti-hypertensive
EARLY ENTRY This candidate is newly indexed — supporting evidence is still being added. Have a paper or data point? Contribute below.
status 2 / 5 · 0 verified on platform
prediction metrics boltz-2 1.0
ipTM0.648
pTM0.740
avg pLDDT85.2
ranking score0.811
STRUCTURE · PEP-04813 × ACE
ranking0.811
target interface 4.5Å peptide drag rotate · ctrl+scroll zoom · right-click pan
boltz-2 1.0 · mmCIF ↓ download
sequence7 aa
157
FRAHPFL
Hypotheses4 directions▾ collapse

Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.

openupdated 2026-06-05

Could this blood-pressure peptide be mostly inactive until your digestive system chops it into its working form?

If true, the real active ingredient is a shorter fragment produced during digestion, meaning lab tests on the whole peptide understate how well it actually works in a living body. For researchers and formulators, this would mean the right target to study and refine is the digested fragment, not the original sequence.

The hypothesis
FRAHPFL functions as a pro-drug-type ACE inhibitor: it is not maximally active as an intact heptapeptide but yields a more potent ACE-inhibitory fragment (HPFL or PFL) after partial luminal proteolysis in the gastrointestinal tract, such that in vivo activity exceeds the in vitro IC50 measured with the intact sequence.
Why it’s plausible
Several food-derived ACE inhibitory peptides (e.g., LKPNM from fish protein) are prodrug-type inhibitors that require gastrointestinal or plasma peptidase processing to release the pharmacologically active shorter peptide. FRAHPFL contains the sequence -H-P-F-L at its C-terminal half. HPFL or PFL are structurally plausible ACE inhibitors: PFL ends in F-L (strong zinc-binding tail) and its N-terminal proline would confer proteolytic resistance. Cleavage of the N-terminal F-R-A block by brush-border peptidases is feasible given that Arg-Ala is a preferred cleavage site for neutral endopeptidases.
Why it matters
If FRAHPFL is a prodrug, in vitro IC50 measurements underestimate true physiological potency and the active metabolite identity must be established before any structure-activity optimization campaign can be correctly directed.
Plausibility.60
Novelty.47
Impact.67
Basis · grounding2 papers · 1 computed/note
[1]
paper
Peptide was isolated from an enzymatic hydrolysate, so the sequence already exists in a proteolytic context; the paper references Fujita & Yoshikawa 1999 (LKPNM as a prodrug ACE inhibitor) directly in its citations
doi: 10.1016/j.foodchem.2010.12.039
[2]
sequenceR-A at positions 2-3 is a candidate trypsin/brush-border protease cleavage site; the resulting C-terminal fragment HPFL terminates in -F-L, a recognized ACE-inhibitory C-terminal motif
[3]
paper
Axis hit states that ACE inhibitory peptides must reach the cardiovascular system in active form, implying gastrointestinal processing is a decisive step
doi: 10.1079/bjn20041189
openupdated 2026-06-05

Does one specific building block in this peptide act like a hinge that holds the active end in the right shape to block a blood-pressure enzyme?

If swapping out that proline consistently wrecks potency, it confirms exactly which part of the peptide to preserve or reinforce when designing stronger versions. That would give peptide engineers a clear and validated starting point rather than trial-and-error modifications.

The hypothesis
The proline at position 5 of FRAHPFL introduces a rigid cis-capable backbone kink that locks the C-terminal -F-L dipeptide into a presentation geometry that pre-organizes the zinc-binding leucine carboxylate, and substituting this proline with any flexible amino acid reduces ACE inhibitory potency by at least one order of magnitude.
Why it’s plausible
Proline is the only amino acid that can adopt a cis peptide bond at physiological frequency and introduces a fixed phi-angle constraint. In a heptapeptide, the proline at position 5 would rigidify the orientation of Phe-6 and Leu-7 relative to the upstream chain. For ACE inhibition, optimal C-terminal display is critical: the zinc-binding carboxylate of Leu-7 must be positioned correctly relative to the enzyme zinc. The proline kink, by restricting backbone flexibility, would reduce the entropic cost of binding and pre-organize the pharmacophore. Loss of this proline, replaced by glycine or alanine, would increase conformational entropy and likely diminish affinity.
Why it matters
Confirming the proline as a conformational anchor would guide engineering of more potent analogs: N-methylation of the proline nitrogen or introduction of a 4-hydroxyproline could further tune rigidity and bioavailability simultaneously.
Plausibility.57
Novelty.48
Impact.58
Basis · grounding1 paper · 2 computed/notes
[1]
sequencePro at position 5 separates the His-4 residue from the C-terminal Phe-Leu; its unique backbone constraint distinguishes FRAHPFL from flexible heptapeptides
[2]
paper
Structure-function axis text explicitly states that amino acid composition and sequence govern antihypertensive activity, calling for studies of the kind proposed here
doi: 10.1021/jf5002606
[3]
structureBoltz-2 structure was computed; even without interface confidence details, a computed structure for a 7-residue peptide with proline would show distinct turn geometry influencing C-terminal presentation
openupdated 2026-06-05

What if a single peptide from food could block both of the main enzymes that drive high blood pressure, instead of just one?

Drugs that block both enzymes at once tend to lower blood pressure more effectively than single-target drugs, but existing versions carry a serious side-effect risk. If this food-derived peptide turns out to work on both, it could open a safer, oral route to the same dual effect, which would interest both functional food developers and pharmaceutical researchers.

The hypothesis
FRAHPFL inhibits neprilysin (neutral endopeptidase, NEP/CD10) in addition to ACE because its proline-containing sequence matches the substrate recognition profile of neprilysin, which cleaves at the N-terminal side of hydrophobic residues and whose active site accommodates the Phe-6/Leu-7 tail of FRAHPFL.
Why it’s plausible
Neprilysin and ACE are both zinc metallopeptidases with overlapping substrate pools including bradykinin, enkephalins, and natriuretic peptides. Dual ACE/NEP inhibitors (vasopeptidase inhibitors) produce superior blood pressure reduction by simultaneously blocking angiotensin II production and preventing natriuretic peptide degradation. FRAHPFL presents a zinc-chelating C-terminus and a hydrophobic Phe in the S1 position relative to Leu-7, which matches neprilysin's preference for hydrophobic P1 residues. Food-derived peptides have not been systematically screened against neprilysin despite the structural rationale.
Why it matters
A single food-derived heptapeptide with dual ACE and NEP inhibition would constitute a safer, orally active vasopeptidase inhibitor and circumvent the angioedema risk associated with synthetic vasopeptidase inhibitors like omapatrilat, motivating a new functional food development pathway.
Plausibility.45
Novelty.58
Impact.63
Basis · grounding2 papers · 1 computed/note
[1]
sequenceC-terminal -P-F-L provides a phenylalanine in the P1 position relative to neprilysin cleavage preference (hydrophobic at P1); the zinc-binding Leu carboxylate mirrors ACE-inhibitor pharmacophore geometry
[2]
paper
Review discusses that antihypertensive peptides act through multiple mechanisms in the cardiovascular system, including pathways beyond ACE inhibition
doi: 10.1038/s41392-024-02107-5
[3]
paper
Notes peptides with antihypertensive effects are investigated across cardiovascular, endocrine, and nervous systems, implying multi-target potential is recognized but not systematically exploited
doi: 10.1016/j.foodchem.2012.08.080
openupdated 2026-06-05

Could a minor structural change make this peptide survive in the bloodstream long enough to actually do something useful?

Food-derived peptides often get destroyed in the blood before they can reach their target, which is why so many promising lab results fail in living systems. If this modification extends survival without hurting potency, it could be the step that bridges a food ingredient lead all the way to a serious drug candidate.

The hypothesis
Introducing a D-amino acid substitution at the arginine (position 2) of FRAHPFL to give F-dR-A-H-P-F-L preserves ACE inhibitory potency while conferring resistance to serum proteases and extending plasma half-life, because the positively charged guanidinium side chain (which is achiral in terms of its electrostatic contribution) continues to satisfy the ACE S2' subsite while the D-backbone configuration sterically occludes protease active sites that require L-amino acid geometry.
Why it’s plausible
D-amino acid substitution is an established strategy to increase proteolytic stability of bioactive peptides without abolishing target binding when the substitution is at a position not directly contacting the catalytic machinery. Arginine at position 2 is one residue removed from the N-terminus and lies outside the proposed C-terminal zinc-binding pharmacophore (positions 5-7). Its side chain charge may interact with the ACE anionic S2' subsite, a contact that is charge- and length-dependent rather than stereospecific. The proteolytic stability axis hit (score 0.713) from a paper on D-amino acid substitution directly supports this engineering hypothesis.
Why it matters
If confirmed, this substitution would produce a minimally modified analog with a longer plasma half-life suitable for in vivo efficacy studies, bridging the gap between food-derived lead and pharmaceutical candidate without changing the core pharmacophore.
Plausibility.55
Novelty.33
Impact.55
Basis · grounding2 papers · 1 computed/note
[1]
paper
Proteolytic stability axis hit states that D-amino acid substitution improves peptide stability in serum and inhibits enzymatic recognition by endogenous proteases, with design rationale grounded in established literature
doi: 10.1248/cpb.c25-00478
[2]
sequenceArg at position 2 is two residues from the N-terminus and outside the proposed C-terminal ACE pharmacophore (-H-P-F-L), making it a candidate for stereospecific substitution with minimal effect on binding
[3]
paper
Half-life axis hit references strategies to improve plasma half-life of peptide and protein drugs, indicating this is an active and validated engineering direction
doi: 10.1128/jvi.01840-06
details expand to inspect
full evidence table2 metrics
metricvaluetool
ipTM 0.6481613516807556 boltz-2
ranking score 0.8109986186027527 boltz-2
3-letter notation
Phe-Arg-Ala-His-Pro-Phe-Leu
recipeboltz-2 1.0
parametervalue
modelboltz-2 1.0
weights
hardwarenvidia_nim_api
mlx version
python
random seed
msa strategycolabfold_nvidia
diffusion samples1
runtime
predicted bymlx@peptide
predicted at2026-04-25
citationbibtex
peptidemodel (2026). Blood-pressure-lowering peptide (FRAHPFL) (pep-04813, v1). PeptideModel. https://peptidemodel.com/card/pep-04813
@peptide{pep04813,
  sequence = {FRAHPFL},
  target   = {ace},
  author   = {peptidemodel},
  year     = {2026},
  status   = {bioassayed}
}
related peptides 2 by signal overlap
references 1 papers
discussion no comments
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