How Research Peptides Are Made

Nearly all research peptides are produced by solid-phase peptide synthesis, a method introduced by Bruce Merrifield in 1963 and still the dominant route for chains under roughly fifty residues.

Solid-phase synthesis

The growing chain is anchored to a resin bead. Each cycle adds one protected amino acid, then removes the protecting group so the next can couple. Because the product stays bound to the resin, excess reagents are simply washed away.

Recombinant expression

Longer sequences are more economically produced by expressing them in bacterial or yeast systems. This route introduces different impurity profiles, including host-cell proteins.

Reading purity claims

Purity is usually reported by HPLC as area percentage. It says nothing about endotoxin load, residual solvents, counter-ion content, or whether the sequence is the one claimed — which requires mass spectrometry.