One-to-three amino acid converter

Convert single-letter amino acid codes to three-letter format. Upload a file or paste your amino acid sequences below.

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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 acidOne-letter codeThree-letter code
AlanineAAla
ArginineRArg
AsparagineNAsn
Aspartic acidDAsp
Asparagine or Aspartic acid*BAsx
CysteineCCys
Glutamic acidEGlu
GlutamineQGln
Glutamine or Glutamic acid*ZGlx
GlycineGGly
HistidineHHis
IsoleucineIIle
LeucineLLeu
LysineKLys
MethionineMMet
PhenylalanineFPhe
ProlinePPro
SerineSSer
ThreonineTThr
TryptophanWTrp
TyrosineYTyr
ValineVVal
Unknown*XXaa

Note: The special codes 'B', 'Z', and 'X' represent ambiguous amino acids.