What is one-to-three (amino acid conversion)?
"One-to-three" conversion refers to the process of translating a single-letter amino acid code into its three-letter abbreviation. This is a common practice in bioinformatics and biochemistry for interpreting and representing protein sequences.
- Protein sequencing: Proteins are made of long chains of amino acids. These chains are represented in text format using abbreviations for each amino acid.
- Convenience vs. clarity: The one-letter code is a compact and efficient way to write long protein sequences, while the three-letter code is often used for clarity, especially in a clinical or educational context.
- Specialized tools: Many online tools and software applications perform this conversion. A user can paste a raw protein sequence (e.g.,
KVFGRCEL...) into a text box, and the tool will automatically convert it into the three-letter format (e.g.,Lys Val Phe Gly Arg...).
One-to-three conversion table
The table below lists the standard one-letter and three-letter codes for the 20 common amino acids.
| Amino acid | One-letter code | Three-letter code |
|---|---|---|
| Alanine | A | Ala |
| Arginine | R | Arg |
| Asparagine | N | Asn |
| Aspartic acid | D | Asp |
| Asparagine or Aspartic acid* | B | Asx |
| Cysteine | C | Cys |
| Glutamic acid | E | Glu |
| Glutamine | Q | Gln |
| Glutamine or Glutamic acid* | Z | Glx |
| Glycine | G | Gly |
| Histidine | H | His |
| Isoleucine | I | Ile |
| Leucine | L | Leu |
| Lysine | K | Lys |
| Methionine | M | Met |
| Phenylalanine | F | Phe |
| Proline | P | Pro |
| Serine | S | Ser |
| Threonine | T | Thr |
| Tryptophan | W | Trp |
| Tyrosine | Y | Tyr |
| Valine | V | Val |
| Unknown* | X | Xaa |
Note: The special codes 'B', 'Z', and 'X' represent ambiguous amino acids.
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