Amino Acid Code Converter
How to convert between one-letter and three-letter amino acid codes
- Choose the direction: one-letter to three-letter codes, or three-letter back to one-letter.
- Paste the protein. Three-letter codes can be written as Met-Lys-Val or MetLysVal; spaces, hyphens and numbers are ignored.
- For three-letter output, choose the separator and how many residues go on each line. Copy output or Download saves the result.
Frequently asked questions
What happens to * and X?
A stop (*) becomes Ter and X becomes Xaa. B, Z, J, U and O become Asx, Glx, Xle, Sec and Pyl.
What if a code is not recognized?
The tool stops and names the first group of three letters that is not an amino acid code, so you can fix it.
Is my sequence uploaded?
No. Everything runs in your browser, so your sequences never leave your device.