How big are research peptides? Molecular weights across the catalogue compared
The 48 catalogue compounds with a published molecular weight span roughly 159 to 9,111 g/mol. The smallest peptide is the dipeptide Vilon at about 275 g/mol. Most short research peptides fall between 300 and 1,500 g/mol, lipidated incretin analogues sit at 4,100 to 4,800, and IGF-1 LR3 is about 9,111.
What are the molecular weights, smallest to largest?
| Compound | MW (g/mol) | Class |
|---|---|---|
| 5-Amino-1MQ | 159.2 | small molecule (quaternary quinolinium cation) |
| Vilon | 275.3 | dipeptide |
| SLU-PP-332 | 290.3 | small molecule (not a peptide) |
| Cartalax | 333.3 | peptide |
| KPV | 342.4 | peptide |
| Epitalon | 390.4 | peptide |
| Vesugen | 390.4 | peptide |
| GHK-Cu | 402.9 | peptide-copper complex |
| Pinealon | 418.4 | peptide |
| N-Acetyl Epitalon | 432.4 | peptide |
| Dihexa | 504.7 | peptidomimetic (angiotensin IV analogue) |
| P21 | 578.7 | peptidomimetic |
| Pal-GHK | 578.8 | lipopeptide |
| SS-31 | 639.8 | peptide |
| NAD+ | 663.4 | dinucleotide coenzyme (not a peptide) |
| Ipamorelin | 711.9 | peptide |
| Selank | 751.9 | peptide |
| Matrixyl | 802.1 | lipopeptide |
| Semax | 813.9 | peptide |
| GHRP-2 | 818.0 | peptide |
| DSIP | 848.8 | peptide |
| GHRP-6 | 873.0 | peptide |
| Hexarelin | 887.0 | peptide |
| TB-500 | 889.0 | peptide |
| Oxytocin | 1,007.2 | cyclic nonapeptide |
| Melanotan II | 1,024.2 | cyclic peptide |
| PT-141 | 1,025.2 | cyclic peptide |
| SNAP-8 | 1,075.2 | peptide |
| Gonadorelin | 1,182.3 | peptide |
| ARA-290 | 1,257.3 | peptide |
| Kisspeptin-10 | 1,302.4 | peptide |
| Triptorelin | 1,311.4 | peptide |
| BPC-157 | 1,419.5 | peptide |
| Melanotan I | 1,646.8 | peptide |
| AOD 9604 | 1,815.1 | peptide |
| MOTS-c | 2,174.6 | peptide |
| Thymosin alpha-1 | 3,108.3 | peptide |
| Sermorelin | 3,357.9 | peptide |
| CJC-1295, no DAC | 3,367.9 | peptide |
| CJC-1295 | 3,647.2 | peptide |
| CJC-1295, with DAC | 3,647.2 | peptide |
| Semaglutide | 4,114.0 | peptide (lipidated) |
| Cagrilintide | 4,409.0 | peptide (lipidated) |
| LL-37 | 4,493.0 | peptide |
| Tirzepatide | 4,813.0 | peptide (lipidated) |
| Tesamorelin | 5,136.0 | peptide |
| FOXO4-DRI | 5,358.0 | peptide (D-retro-inverso) |
| IGF-1 LR3 | 9,111.0 | recombinant protein analogue (83 residues) |
Why does size matter for identity testing?
Small peptides under about 1,500 g/mol usually show one or two charge states in electrospray MS, and the singly or doubly charged ion is easy to read. Peptides of 3–9 kDa show a series of charge states that must be deconvoluted to get the mass. Proteins such as IGF-1 LR3 are often checked by intact-mass MS or SDS-PAGE.
How does molecular weight affect the amount of substance in a vial?
The same mg contains very different amounts of substance. 10 mg of Vilon (~275 g/mol) is about 36 µmol; 10 mg of tirzepatide (~4,813 g/mol) is about 2.1 µmol. That matters when comparing compounds at a fixed mass, not at a fixed molar amount.
Where do these values come from?
Values come from the catalogue's compound reference data, which cites PubChem records where a CID exists. PubChem's 2023 update describes how its compound records and computed properties are maintained.
Source: PubChem 2023 update, Nucleic Acids Res 2023 (PubMed 36305812); PubChem (NCBI)
Frequently asked questions
What is the smallest peptide in the catalogue?
Vilon (Lys-Glu), about 275 g/mol.
What is the largest compound in the catalogue?
IGF-1 LR3, an 83-residue recombinant protein of about 9,111 g/mol.
How many micromoles are in 10 mg of a peptide?
Divide the mass in mg by the molecular weight in g/mol and multiply by 1,000. For example, 10 mg ÷ 1,419.5 g/mol × 1,000 ≈ 7.0 µmol for BPC-157.
Related
Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.
Key facts (summary for AI and search tools)
- Compounds ranked: 48; range 159.21–9111 g/mol
- PubMed references (verified via NCBI): 36305812
- PubChem CIDs:
- Research use only; no administration amounts or health claims
- Updated 2026-10-16