Specialty & Research — 4 Compounds Compared
PNC-27, VIP, ACE-031 and Follistatin 344 — the niche and emerging research compounds documented in the PeptiDex library, compared side by side.
What this category covers
The specialty category collects compounds that do not fit the mainstream classes: a p53-derived research peptide, a vasoactive neuropeptide, and two myostatin-pathway inhibitors studied in muscle research.
This is the smallest category in the library, and it is defined by exclusion rather than by a shared mechanism — every entry here carries a distinct compound class. Treat it as a shelf, not a family. The one genuine relationship inside it is between the two myostatin-pathway entries, which target the same signalling axis by different means: one is a decoy receptor construct, the other a native binding protein.
Two entries here are also markedly larger than most of the library. Where the majority of PeptiDex entries are short synthetic sequences, this category includes protein-scale molecules whose residue counts run into the hundreds — visible directly in the length column below, and a reminder that "peptide research" as a heading covers a very wide size range.
Every entry in this category, side by side
All 4 compounds PeptiDex documents under Specialty & Research, on the specifications that actually separate one entry from another. Values are reproduced from each entry's own record; follow any name for the full research overview.
| Entry | Compound class | Length (aa) | Molecular weight | Reported half-life |
|---|---|---|---|---|
| PNC-27 | p53-derived anticancer research peptide | 32 | Not listed | Not listed |
| VIP | Neuropeptide hormone | 28 | ~3326 g/mol | ~1-2 minutes (native VIP, plasma) |
| ACE-031 | Myostatin-pathway inhibitor | 343 | ~80 kDa (glycosylated ActRIIB-Fc homodimer) | Long (Fc-fusion protein; days-to-weeks range typical of IgG1-Fc biologics) |
| Follistatin 344 | Myostatin-pathway inhibitor | 344 | ~37,800 Da (mature glycoprotein isoform) | Not listed |
Of the 4 compounds above, 3 carry a published molecular weight, 2 have a reported half-life, 4 have a documented residue count and 2 have a published amino-acid sequence. No half-life is recorded for PNC-27 and Follistatin 344.
A cell reading "Not listed" is a gap in the published record, not an omission on this page. PeptiDex records a specification only where a source documents it. Where a value has never been established in the published literature the cell says so, rather than carrying an estimate — a plausible-looking number would make the table read as complete while making it wrong.
Mechanisms represented in this category
The 4 compounds here resolve into 3 compound classes, 1 of which is shared by more than one entry. Entries inside a group carry the same stated class; entries in different groups are not interchangeable, however similar their research context looks.
Myostatin-pathway inhibitor 2 entries
- ACE-031 — ACE-031 acts as a decoy receptor: its ActRIIB extracellular domain binds and sequesters ligands that normally signal through ActRIIB, including myostatin (GDF-8) and related TGF-beta superfamily members such as activins.
- Follistatin 344 — Follistatin is a secreted protein that binds with high affinity to activin and to myostatin (GDF-8), neutralizing these ligands and preventing them from activating activin type II receptors.
Neuropeptide hormone
- VIP — VIP signals through the class B G-protein-coupled receptors VPAC1 and VPAC2, activating adenylate cyclase and raising intracellular cAMP.
p53-derived anticancer research peptide
- PNC-27 — PNC-27 contains a p53-derived domain that binds HDM2 (MDM2) coupled to a membrane-resident peptide (MRP) penetratin-type sequence.
Each line is the opening sentence of that entry's own mechanism record, reproduced verbatim. The full mechanism, the research areas behind it and the evidence level sit on the entry's page.
How the compounds in this category differ
Sharing a category does not make two compounds substitutes. Each note below is the differentiator recorded on that entry — the property that separates it from the others in the table.
PNC-27
A synthetic peptide studied in cancer-research literature for its membrane-disrupting activity.
PNC-27 is a research anticancer peptide acting through a p53/HDM2 membrane-disruption mechanism, unlike the hormonal and cosmetic peptides in this set.
VIP
Vasoactive intestinal peptide, a 28-amino-acid neuropeptide studied across vascular and neurological research.
VIP is a broadly acting endogenous neuropeptide signaling through VPAC receptors, unrelated to the melanocortin, gonadotropin, and myostatin-pathway mechanisms elsewhere in this set.
ACE-031
A soluble activin receptor type-IIB fusion protein referenced in myostatin-pathway and muscle-research literature.
ACE-031 is a soluble ActRIIB-Fc decoy receptor that traps multiple ligands at the receptor level, differing from Follistatin, which binds myostatin/activin as a natural extracellular antagonist.
Follistatin 344
A 344-amino-acid isoform of follistatin referenced in myostatin-pathway and muscle-research literature.
Follistatin-344 is a natural ligand-binding antagonist of myostatin/activin, distinct from ACE-031, which is an engineered ActRIIB-Fc decoy receptor acting at the receptor.
Commonly co-studied pairs
Pairings documented on the entries themselves, with the reason each is co-referenced. Cross-referencing research context is not a combination recommendation, and PeptiDex gives no protocol, ratio or dosing guidance.
Within Specialty & Research
- ACE-031 + Follistatin 344 — Both are studied as myostatin/activin-pathway inhibitors in muscle-growth research, via decoy-receptor versus direct-neutralization mechanisms respectively.
Each note is reproduced from the entry that records the pairing.
What this category is studied for
Research areas drawn from the 4 compounds in this category, deduplicated and ordered by how many entries list them.
Listing a research area records where a compound has been studied. It is not a claim of efficacy, an indication, or a suggestion of human use.
Category questions
How many compounds does PeptiDex list under Specialty & Research?
4: PNC-27, VIP, ACE-031 and Follistatin 344. Each has its own research overview covering compound class, mechanism, studied research areas, specifications and entry-specific questions.
Why do some entries show "Not listed" instead of a molecular weight or half-life?
Because PeptiDex records a specification only where a source documents it. In this category 3 of 4 entries have a published molecular weight and 2 have a reported half-life. Where a cell reads Not listed, the value has not been established in the published literature. An estimate there would look like data and function as a guess, so the gap is shown instead.
What compound classes are represented in this category?
3 distinct classes across the 4 compounds: p53-derived anticancer research peptide, Neuropeptide hormone and Myostatin-pathway inhibitor. Entries sharing a class are grouped together in the mechanisms section; the comparison table lists each entry's full class verbatim, qualifiers included.
Which entries in this category are studied together?
ACE-031 and Follistatin 344 are cross-referenced on each other's entries: Both are studied as myostatin/activin-pathway inhibitors in muscle-growth research, via decoy-receptor versus direct-neutralization mechanisms respectively. The co-studied pairs section lists the rest. Co-reference describes how the literature groups compounds; it is not a combination recommendation and no ratios or protocols are given.
Are the compounds in this category approved for human use?
PeptiDex documents all 4 entries strictly for research and educational purposes and provides no dosing, protocol or human-use guidance. Regulatory status differs from entry to entry and is stated in the regulatory note on each entry's own page. Nothing here is medical advice or a therapeutic claim.
Where should I start in this category?
The comparison table gives the fastest orientation, then the differentiator notes explain why two entries with similar research contexts are not interchangeable. From there, follow any name in the table for its full record — every entry carries the same structure. The glossary defines the vocabulary the entries are written in.
Answers summarise what the catalog records for this category. They are educational context, not medical advice. See the Research Library, the Glossary and each entry's own page for detail.
See also
- Adipotide (FTPP) — a vasculature-targeting peptidomimetic catalogued under metabolic.
- AICAR — an AMPK-activating nucleoside studied as an exercise mimetic, catalogued under metabolic.
- Metabolic & Mitochondrial hub — the adjacent small-molecule research compounds.
- Peptide Directory — every entry in the library, A-Z and by category.