Peptide Nomenclature: How Peptides Get Their Names

Why Peptide Names Look So Strange

If you’re new to peptide research, the names can feel like alphabet soup. BPC-157. TB-500. GHK-Cu. AOD-9604. PT-141. Where do these names come from, and what do they actually tell you?

The answer is: it depends. Peptides are named using several different conventions depending on who named them, when, and why. Understanding those conventions makes it much easier to read research papers, decode product labels, and understand what you’re working with.

Convention 1: Named After Their Source

Some peptides are named after the tissue or protein they were originally isolated from.

BPC-157 stands for Body Protection Compound-157. It was isolated from gastric juice — the body’s own digestive fluid — and the number refers to its position in a larger protein sequence. The “body protection” reflects the original research hypothesis that it protected stomach lining.

TB-500 is derived from Thymosin Beta-4, a protein produced by the thymus gland. The “500” refers to its molecular structure. (TB-500 is actually a fragment of Thymosin Beta-4, not the full protein.)

GHK-Cu is named by its amino acid composition: Glycine-Histidine-Lysine (GHK) bound to a copper ion (Cu). Simple and descriptive.

Convention 2: Named After Their Function or Target

Other peptides are named for what they do or what they target.

GHRP-6 stands for Growth Hormone Releasing Peptide-6 — it releases growth hormone, and the “-6” refers to its six amino acid chain length. GHRP-2 is the two-amino-acid-shorter variant with a different potency and side effect profile.

CJC-1295 was named by the laboratory that created it (Conjuchem), and the number is essentially an internal code. Its function (growth hormone secretion) is what defines it in practice.

IGF-1 LR3 stands for Insulin-like Growth Factor-1, Long R3. The “Long R3” refers to a structural modification — an arginine substitution (R3) and a 13-amino-acid extension that makes it longer-acting than native IGF-1.

Convention 3: Internal Lab Codes and Development Numbers

Many synthetic peptides, especially newer ones from pharmaceutical development, are named with alphanumeric codes that reflect their origin in a drug development program.

AOD-9604 stands for Anti-Obesity Drug, compound 9604 — developed specifically to target fat metabolism without the growth-promoting effects of full HGH. The number is simply its identifier in the development pipeline.

PT-141 (Bremelanotide) was developed as compound #141 in a palatin technologies melanocortin research program. PT = Palatin Technologies.

HGH Fragment 176-191 is named with total clarity: it is the fragment of Human Growth Hormone spanning amino acid positions 176 through 191 in the HGH sequence.

Convention 4: Named After Their Amino Acid Sequence

Some shorter peptides are simply named by spelling out their amino acid composition.

KPV is Lysine-Proline-Valine — three amino acids, named in sequence. Simple, accurate, and directly descriptive.

LL-37 is a 37-amino-acid cathelicidin peptide where the first two amino acids are both Leucine (L-L), giving it its prefix. The 37 is the total chain length.

Epithalon (also spelled Epitalon) is a tetrapeptide (4 amino acids) — Ala-Glu-Asp-Gly — named from its source in the pineal gland (epithalamus).

Why Naming Matters for Researchers

Understanding nomenclature helps you:

• Identify fragments vs full proteins: “Fragment 176-191” tells you it’s a piece of something larger. “LR3” tells you it’s a modified version of a native molecule.
• Spot structural variants: GHRP-2 and GHRP-6 are related but distinct. CJC-1295 with DAC vs without DAC are meaningfully different in duration of action.
• Read literature more accurately: Research papers use the chemical name or IUPAC designation — knowing what commercial names correspond to which compounds prevents confusion.
• Evaluate vendor claims: If a vendor labels a product with a name that doesn’t correspond to any known nomenclature system, that’s a red flag worth investigating.

A Note on INN Names

When peptides advance into clinical development, they receive International Nonproprietary Names (INN) — standardized names assigned by the WHO. Semaglutide, tirzepatide, and retatrutide are all INN names. They typically end in specific suffixes that indicate drug class (-glutide for GLP-1 agonists, -tide for peptides generally).

Research peptides that haven’t reached this stage often stick with their lab code or descriptive names. This is why you’ll see “BPC-157” and “AOD-9604” as permanent names rather than generic names — they haven’t been through an INN assignment process.

Written by the NorthPeptide Research Team