How many residues is a pentadecapeptide?

Fifteen, penta for five plus deca for ten.

Is BPC-157 a protein?

No. At fifteen residues it is firmly a peptide; the conventional boundary sits around fifty residues where chains begin folding reliably.

Why does the literature always say 'stable gastric pentadecapeptide'?

It is the Zagreb group's consistent phrasing, and searching the full phrase efficiently isolates their output.

What Pentadecapeptide Means

The short answer

Pentadecapeptide means a peptide of fifteen amino acid residues, penta for five, deca for ten. BPC-157 is one, which places it above the short signalling peptides and well below anything that would fold into a protein.

Key facts

Penta: Five
Deca: Ten
Pentadeca: Fifteen
BPC-157: 15 residues, 1419.5 Da
Comparison (Selank): 7 residues
Comparison (MOTS-c): 16 residues
Comparison (retatrutide): 39 residues

The counting convention

Peptides are frequently named by length using Greek numerals: tripeptide for three, heptapeptide for seven, nonapeptide for nine, pentadecapeptide for fifteen. The convention is compact and precise, and encountering it in a paper title tells you the molecule's size before you read anything else.

Where fifteen sits

Comfortably in peptide territory, nowhere near protein. GHK is three residues, Selank and Semax seven, TB-500 seven, DSIP nine, MOTS-c sixteen. Thymosin beta-4 at 43 and retatrutide at 39 are large peptides; insulin at 51 is conventionally the smallest thing routinely called a protein. Fifteen is mid-range among research peptides.

Research material referenced

BPC-157 5mg, third-party HPLC tested

Buy BPC-157 · £15.99

What that size permits

Fifteen residues is long enough to contain distinct structural elements. BPC-157's polyproline segment and its flexible glycine hinges are separate features within one molecule, which a heptapeptide could not accommodate. It is short enough for straightforward solid-phase synthesis, though the proline content complicates that.

The peptide-protein boundary

There is no sharp line, and the usual convention places it somewhere around 50 residues, the point at which a chain reliably folds into a stable tertiary structure. Below it, chains generally sample many conformations. The distinction is about behaviour rather than an arbitrary count, which is why it is fuzzy.

Why the name is used so consistently here

The Zagreb literature almost invariably writes stable gastric pentadecapeptide BPC 157 rather than just BPC-157. Searching that full phrase is an efficient way to find the group's output specifically, and the consistency of the phrasing is itself a marker of a single research programme.

Frequently asked questions

How many residues is a pentadecapeptide?: Fifteen, penta for five plus deca for ten.
Is BPC-157 a protein?: No. At fifteen residues it is firmly a peptide; the conventional boundary sits around fifty residues where chains begin folding reliably.
Why does the literature always say 'stable gastric pentadecapeptide'?: It is the Zagreb group's consistent phrasing, and searching the full phrase efficiently isolates their output.

Extended research context

The BPC-157 (Pentadecapeptide) deep dive

Deep dive: the pentadecapeptide sequence

BPC-157 is a synthetic pentadecapeptide with the sequence Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val. It is derived from a fragment identified in human gastric juice by the Zagreb research group (Sikirić and colleagues), whose body of published work spans three decades and covers models ranging from tendon repair to gut integrity. The 'BPC' initials stand for 'body protection compound', the group's original characterisation term.

Two forms: acetate salt vs arginate

BPC-157 is supplied most commonly as an acetate salt; a small subset of suppliers offer the arginate form, which has slightly different solubility and stability properties. For research reproducibility, keep the salt form consistent across a study and confirm which form the CoA specifies (mass ± counterion changes the reading).

Reading a BPC-157 CoA

A trustworthy BPC-157 CoA lists HPLC purity (target ≥98% area), mass-spec confirmation (~1,419 Da for the free peptide), water content (Karl Fischer), acetate content, and residual solvents. Some batches also include endotoxin data. Any missing category is a red flag for a compromised supply chain.

Research applications

▸Cell-culture models of gut epithelial integrity
▸Tendon fibroblast migration and collagen-synthesis assays
▸Angiogenesis models involving VEGF and NO signalling
▸Stability studies comparing acetate vs arginate salt forms
▸Analytical reference for pentadecapeptide HPLC methods

Handling checklist

✓Store lyophilised vial at −20 °C long-term (2–8 °C short-term)
✓Reconstitute with bacteriostatic water; a 5 mg vial dissolves cleanly
✓Aliquot reconstituted solution; keep refrigerated 2–8 °C, use within 28 days
✓Protect from light and repeated warming
✓Verify CoA: HPLC ≥98%, mass ~1,419 Da, salt form declared

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Mixing acetate and arginate BPC-157 across a study

Fix: Choose one salt form and stay with it. Different masses and solubility.

✗ Assuming stability at room temperature

Fix: Refrigerate reconstituted solution; discard after 28 days.

✗ Buying without a CoA

Fix: Only source from suppliers that publish batch HPLC + mass-spec data.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

UKP

Written and reviewed by

The UK Peptides Editorial Team · Research library, UK Peptides

The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.

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