A peptide's molecular weight is the combined mass of all its amino acids, measured in daltons. It is used to confirm a peptide's identity by mass spectrometry and to help calculate concentrations.
What molecular weight is
Each amino acid has a known mass. Add them together (accounting for the water released as peptide bonds form) and you get the peptide's molecular weight. It is essentially the peptide's fingerprint on the scale.
How it confirms identity
Because every sequence has an expected molecular weight, mass spectrometry can confirm identity by checking whether the measured mass matches. A match is strong evidence the peptide is what the label says.
Browse research-grade peptides
Every Axis compound is third-party tested to 99.4%+ purity, with a certificate of analysis on every batch.
A role in concentration
Molecular weight also appears in some concentration calculations, particularly when converting between mass and molar amounts. For everyday reconstitution math, the calculator works directly in milligrams and milliliters.
Key takeaways
- Molecular weight is the combined mass of a peptide's amino acids.
- It is measured in daltons.
- Mass spectrometry uses it to confirm identity.
- It also factors into some concentration calculations.
A note on research use
The peptides supplied by Axis Peptide Labs are reference compounds for laboratory and research use only. They are intended for qualified researchers working in academic, institutional, and analytical settings. They are not drugs, foods, cosmetics, or medical products, and they are not intended for human or veterinary consumption. Documented identity and documented purity are what matter most when sourcing a compound, both of which are published on the Axis certificates of analysis page.
