How Research
Peptides Are
Made

Solid-phase peptide synthesis

The great majority of synthetic research peptides are made by solid-phase peptide synthesis (SPPS), a method developed by Bruce Merrifield in the 1960s that earned him a Nobel Prize. Its central idea is to anchor the growing peptide chain to an insoluble solid support — tiny resin beads — so that excess reagents can simply be washed away at each step while the peptide stays put.

The chain is built one amino acid at a time, working from the C-terminus toward the N-terminus. Each amino acid added carries a temporary protecting group so that only the intended reaction occurs; the cycle is a repeating pattern of deprotect, couple the next amino acid, wash, repeat.

Cleavage and purification

Once the full sequence is assembled, the finished peptide is chemically cleaved from the resin and its remaining protecting groups removed. What comes off is not yet pure: it is the target peptide mixed with by-products of the synthesis.

The crude material is then purified, typically by preparative high-performance liquid chromatography, which separates the target peptide from closely related impurities.

Why impurities arise

No coupling step is perfectly efficient. Occasionally an amino acid fails to attach on a given chain, producing a deletion sequence missing one residue, or a chain that terminated early. These are the related substances that purification is designed to remove and that a purity figure on a certificate of analysis accounts for.

Analysis and finishing

Purified material is analysed to confirm what it is: purity by HPLC, identity by mass spectrometry. It is then lyophilised into the stable dry powder in which research peptides are supplied. Every batch we supply is submitted for independent third-party analysis before it is sold.

Frequently Asked Questions

Most synthetic research peptides are made by solid-phase peptide synthesis (SPPS): amino acids are added one at a time to a chain anchored to a solid resin, then the finished peptide is cleaved from the resin, purified, analysed and lyophilised.

Solid-phase peptide synthesis (SPPS) is a method, developed by Bruce Merrifield, in which the growing peptide chain is anchored to insoluble resin beads so excess reagents can be washed away at each step. The chain is built one amino acid at a time.

No coupling step is perfectly efficient, so some chains end up missing a residue (deletion sequences) or terminate early. These related substances are what purification removes and what the purity figure on a certificate of analysis accounts for.