Specialty & Research — 7 Compounds Compared

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 7 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.

Every Specialty & Research entry in the PeptiDex library, compared on compound class, residue count, molecular weight and reported half-life.
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
Abaloparatide	Parathyroid hormone-related peptide analog	Not listed	Not listed	Not listed
Teriparatide	Parathyroid hormone (1–34) analog	Not listed	Not listed	Not listed
Linaclotide	Guanylate cyclase-C agonist	Not listed	Not listed	Not listed

Of the 7 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, Follistatin 344, Abaloparatide, Teriparatide and 1 others.

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 7 compounds here resolve into 6 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.

Guanylate cyclase-C agonist

Linaclotide — Linaclotide is a guanylate cyclase-C agonist studied for local intestinal effects.

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.

Parathyroid hormone analog

Teriparatide — Teriparatide represents the biologically active 1–34 fragment of parathyroid hormone and is studied in bone-remodeling contexts.

Parathyroid hormone-related peptide analog

Abaloparatide — Abaloparatide is a peptide analog related to the parathyroid hormone pathway, studied in bone-formation research.

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.

Abaloparatide

A parathyroid hormone-related peptide analog studied for bone mineral density and fracture outcomes in osteoporosis.

Fracture endpoints and bone mineral density are different outcomes. The open-label teriparatide arm should not be treated as a fully blinded head-to-head comparison.

Teriparatide

A parathyroid hormone fragment studied in osteoporosis research, with trials examining fractures and bone mineral density.

The cited trial concerns a defined osteoporosis population. It does not establish generalized recovery or performance benefits, or equivalence with research-supplier material.

Linaclotide

A guanylate cyclase-C agonist peptide studied in gastrointestinal research, including chronic constipation trials.

Diarrhea was a relevant adverse event in these studies. Trial findings apply to the studied formulation and population, not to unrelated gastrointestinal claims.

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.
Abaloparatide + Teriparatide — Research comparator, not a combination recommendation.

Each note is reproduced from the entry that records the pairing.

What this category is studied for

Research areas drawn from the 7 compounds in this category, deduplicated and ordered by how many entries list them. A further 6 research areas are listed across the individual entries.

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?

7: PNC-27, VIP, ACE-031, Follistatin 344, Abaloparatide, Teriparatide and Linaclotide. 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 7 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?

6 distinct classes across the 7 compounds: p53-derived anticancer research peptide, Neuropeptide hormone, Myostatin-pathway inhibitor, Parathyroid hormone-related peptide analog, Parathyroid hormone analog and Guanylate cyclase-C agonist. 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 7 entries strictly for research and educational purposes. Where an entry reports dosing figures, they are amounts reported in the published research literature, shown for educational context — not instructions, recommendations or protocols for human use. 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.