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The Learn section explains the chemistry behind the compounds in our catalogue. Fundamentals covers what peptides are, how their sequences are written and how peptides are made by solid-phase synthesis. Analytical methods explains how to read a certificate of analysis, what HPLC purity and mass spectrometry identity measure, how purity differs from net peptide content, and how lyophilised material is stored. Compounds gives identity overviews: sequence, structural modifications, molecular formula and mass. Every article is written by the British Peptide Labs editorial team and keeps to identity, structure and analytical data.
What peptides are, how their sequences are written and how they are made.
Peptide storage for sealed lyophilised vials: 2–8 °C short term, −20 °C and below long term, away from light and moisture, without repeated freeze-thaw.
Peptides are chains of amino acids joined by amide (peptide) bonds. How they differ from proteins, and how synthetic peptides are made, specified and analysed.
A lyophilised (lyophilized) peptide is freeze-dried: frozen, then dried under vacuum to a porous cake. The process, the cake, residual water and the vial.
Bacteriostatic water is sterile water with 0.9% benzyl alcohol as a preservative. Its composition, benzyl alcohol chemistry, properties, storage and labelling.
How to read a peptide's amino acid sequence: three- and one-letter codes, N- to C-terminus order, and the notation for Ac-, -NH2, D-residues and cyclisation.
How solid-phase peptide synthesis works: Merrifield's resin method, Fmoc/tBu chemistry, coupling, cleavage, impurities, HPLC purification and freeze-drying.
How identity and purity are measured and reported, and how lyophilised material is stored.
Seven checks for choosing a UK research peptide supplier: HPLC purity, LC-MS identity, independent testing, batch certificates, tracked dispatch and £/mg.
How to read a peptide certificate of analysis field by field: identity by mass spectrometry, HPLC purity, net peptide content, water, issuer and dates.
How HPLC measures peptide purity: reversed-phase columns, acetonitrile gradients, UV detection at 214–220 nm, the area % result and what it leaves out.
HPLC purity and net peptide content measure different things. How counter-ions, residual water and gross mass explain the gap, and how to read both figures.
How mass spectrometry confirms peptide identity: ESI and MALDI-TOF, m/z and charge states, expected vs observed mass, and average vs monoisotopic mass.
Identity overviews: sequence, structural modifications, molecular formula and mass.
Selank vs Semax at the molecular level: tuftsin and ACTH(4–7) cores, the shared Pro-Gly-Pro end, formula, mass, charge and HPLC and LC-MS behaviour.
Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2 (CAS 170851-70-4). Its structure, formula, molecular weight and analysis, explained.
MT2 is a synthetic cyclic heptapeptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 (CAS 121062-08-6). Its lactam ring, amide end, mass and LC-MS explained.
PT-141 (bremelanotide) is a synthetic cyclic heptapeptide, CAS 189691-06-3. Its lactam ring, C-terminal acid, formula, mass and LC-MS analysis explained.
Selank is a synthetic heptapeptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro (CAS 129954-34-3). Its tuftsin core, formula, mass and HPLC and LC-MS analysis explained.
Semax is a synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro (CAS 80714-61-0). Its ACTH(4–7) core, formula, mass and HPLC and LC-MS analysis explained.
Tesamorelin is a synthetic 44-residue GHRH analogue with an N-terminal trans-3-hexenoyl group (CAS 218949-48-5). Formula, mass and LC-MS analysis explained.
GLP-3 (retatrutide, CAS 2381089-83-2) is a 39-residue synthetic lipidated peptide. Its sequence, side chain, formula and molecular mass explained.
BPC-157 is a synthetic 15-residue peptide. Its full sequence, molecular formula, mass, CAS number and analytical profile, explained in chemistry terms.
Cagrilintide is a 37-residue synthetic lipidated peptide with a Cys2–Cys7 disulphide bridge. Its sequence, C20 diacid, formula and mass explained.
GHK-Cu is the copper(II) complex of the tripeptide Gly-His-Lys. How the copper peptide binds Cu(II), its formula, mass, CAS number and how it is analysed.
MOTS-c is a 16-residue peptide encoded in the mitochondrial 12S rRNA gene. Its sequence, molecular formula, mass, CAS number and analysis, explained.
NAD+ is a dinucleotide, not a peptide: two nucleotides joined by a pyrophosphate bridge. Its structure, formula, mass, NAD+/NADH chemistry and analysis.
Semaglutide is a 31-residue synthetic lipidated peptide. Its sequence, Aib8 and Arg34 substitutions, C18 diacid side chain, formula and mass explained.
SS-31 is a synthetic tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2, with a D-arginine and 2′,6′-dimethyltyrosine. Its formula, mass, charge and analysis, explained.
Tirzepatide is a 39-residue synthetic lipidated peptide. Its sequence, two Aib residues, C20 diacid side chain, formula and molecular mass explained.