Glossary
Synthetic (SPPS)
Synthetic peptides are assembled chemically, one residue after another, on a solid resin. What that means for purity, unnatural residues and the COA contents.
In a peptide catalogue, synthetic nearly always means produced by solid-phase peptide synthesis (SPPS): the chain is built chemically, residue by residue, while fixed to an insoluble resin bead, and is then cleaved off and purified. Practically every research peptide shorter than about 50 residues is made this way — BPC-157, semaglutide, ipamorelin and the nootropic peptides included.
What chemical production offers
The chemistry brings three properties. Control is total — unnatural building blocks such as Aib, D-amino acids, acetyl caps and PEG conjugates can be placed at exact positions, something biological expression cannot achieve. Reproducibility is high, since an identical protocol delivers an identical molecule without the biological fluctuation of a cell culture. And there are no contaminants from a host organism, so bacterial endotoxin is not an inherent issue as it is with recombinant material.
The typical impurities are chemical instead: deletion sequences caused by incomplete couplings, truncated chains, protecting groups that were not fully removed, and TFA left over from cleavage. Quantifying exactly these is the job of a certificate of analysis and its HPLC trace.
Related terms
purity · linear peptide