Amino Acid Notation Converter

About Amino Acid Notation Converter

This tool converts a peptide or protein sequence between one-letter codes, three-letter codes and full amino acid names. It detects whether you pasted one-letter or three-letter input, so you can copy from a paper, a mass spectrometry table or a database entry and get the notation another format expects.

How to use it

1. Paste the amino acids into the Amino acids box, as MAKDE or as Met-Ala-Lys-Asp-Glu. Spaces, commas and hyphens between residues are fine.
2. Check the residue badge to see how many residues were recognized.
3. Choose the output in the Convert to menu: One-letter, Three-letter or Full names.
4. Copy the text from the Result panel.

Three-letter to one-letter and back

Met-Ala-Lys-Asp-Glu

One-letter: MAKDE. Full names: Methionine, Alanine, Lysine, Aspartate, Glutamate

When to use it

• Rewriting a mutation table from three-letter to one-letter notation for a figure.
• Expanding a short peptide into full names for a methods description.
• Checking that a pasted three-letter sequence really matches the one-letter sequence in a database.
• Producing a hyphenated three-letter string for a peptide synthesis order.

Questions about Amino Acid Notation Converter

How does it decide the input format?

After splitting on spaces, commas and hyphens, it treats the input as three-letter only if every token is exactly three characters and at least one is a real code such as Met or Ala. Otherwise each character is read as a one-letter code, case insensitively. A FASTA header line is skipped.

Is a three-residue one-letter peptide such as MAK read correctly?

Yes. MAK is a single three-character token, but Mak is not an amino acid code, so it is read as M, A and K. A run that does spell a code, such as ALA, is read as alanine, so add spaces if you mean one-letter A, L, A.

Which residues are supported?

The 20 standard amino acids plus the stop symbol, which is an asterisk in one-letter form and Ter in three-letter form. Selenocysteine, pyrrolysine, Asx, Glx and X are not recognized and are silently dropped.

Can I paste full names?

Not as input; they are output only. The names follow the tool's own list, which uses aspartate and glutamate for D and E.

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