Read a peptide sequence from its N-terminus to its C-terminus, keeping any terminal groups and stereochemical labels. The examples below help you compare a specification with the exact structure named on a report.
Decode the letters in GHK
| Letter | Residue notation | Name |
|---|---|---|
| G | Gly | Glycine |
| H | His | Histidine |
| K | Lys | Lysine |
GHK reads Gly–His–Lys in that order. The supplied GHK-Cu report describes GHK as part of a copper(II) complex, so GHK-Cu and the uncomplexed peptide should retain their different material descriptions.IUPAC sequence notation (opens in a new tab)GHK-Cu report (PDF) (opens in a new tab)
Keep terminal groups visible
| Notation | What it records |
|---|---|
| Ac- at a specified N-terminus | A covalently attached acetyl group |
| -OH at the C-terminus | A terminal carboxyl form |
| -NH2 at the C-terminus | A terminal amide |
| Bracketed residue or position | Read the author’s definition of the change and its location |
The terminal residue and its terminal group are separate details. Acetylation is also different from an acetate counterion. Do not add a terminal group that the source leaves unspecified, and do not read a side-chain amide as a C-terminal amide.IUPAC–IUB — Substituted amino-acid notation (opens in a new tab)Bachem — Frequently asked questions (opens in a new tab)
Compare variants and fragments precisely
D-Ala and L-Ala specify different configurations; D/L is separate from the direction in which the sequence is written. To compare an analogue with a reference sequence, record each changed residue, its position and any terminal modification.IUPAC Blue Book — Amino acids and peptides (opens in a new tab)IUPAC sequence notation (opens in a new tab)
For an illustrative fragment numbered 7–10 inclusive, the length is 10 − 7 + 1 = 4 residues. Retain the reference sequence and whether numbering starts from a precursor or a shorter mature chain: the same printed numbers can otherwise refer to different boundaries.IUPAC sequence notation (opens in a new tab)UniProt — Chain annotation (opens in a new tab)
Reading notation establishes what the specification says. Matching a tested sample to that description is an analytical question; an abbreviation alone does not establish every structural detail.Bachem analytical guide (opens in a new tab)
Sources and further detail
- IUPAC–IUB — One-letter amino-acid notation (opens in a new tab)
Nomenclature recommendations, sections 3AA-20 and 3AA-21; symbols, direction and ambiguous residues.
- IUPAC–IUB — Substituted amino-acid notation (opens in a new tab)
Section 3AA-17: terminal and side-chain notation, with explicit distinctions between hyphens and parentheses.
- Bachem — Frequently asked questions (opens in a new tab)
Salt-form explanation. Bachem's stated supply defaults describe Bachem, not every peptide supplier.
- IUPAC Blue Book — Amino acids and peptides (opens in a new tab)
Sections P-103.1.3 and P-103.3: stereodescriptors and peptide representation. Cysteine prevents a universal L = S shortcut.
- Supplied GHK-Cu 50 mg certificate (opens in a new tab)
MA-GHK-0001, revision 01; task URDL5Q2; lot GHK-01-5Q2. Source of the complex, content and ratio examples. The cited PDF was re-read on 3 October 2026 to check this transcription; its issuer and findings were not independently authenticated.
- Bachem — Quality control of amino acids and peptides (opens in a new tab)
Sections on identity, purity and product content. Used for the distinction between chromatographic area and material content.
- UniProt — Chain annotation (opens in a new tab)
Describes mature chains following processing and multiple chains arising from one precursor.
Revised from the existing source dossier on 3 October 2026. Supplied-report values are document transcriptions, not independent authentication or new measurements. Source notes identify the scope of each reference; this article has not undergone independent scientific peer review.