Aliphatic amino acid. Uncharged, nonpolar, hydrophobic. Has the same chemical formula as isoleucine, but with one of the methyl groups moved to another carbon. Commonly used in DNA binding proteins to dimerize two alpha-helices (see: leucine zipper).

Formula: C6H13NO2
Molecular Weight: 131.17
Three-letter code: Leu
One-letter code: L