Alloisoleucine

**Semantic type:** Amino Acid, Peptide, or Protein

**Definition:** The optically active form of the amino acid alloisoleucine with an L-(2S,3R)-configuration, derived from endogenous L-isoleucine, that is an intermediate in the metabolism of branched-chain amino acids. Detection of alloisoleucine in plasma is diagnostic for maple-syrup urine disease (MSUD).

**Synonyms:** - (2S,3R)-2-Amino-3-Methylpentanoic Acid - ALLOISOLEUCINE, L- - Allo-Ile - Allo-L-Isoleucine - AlloI - Alloisoleucine, L- - Isoleucine, Allo- - Isoleucine, Threo- - L-Isoleucine, 3-Methyl-, Threo- - L-Isoleucine, Allo- - L-Isoleucine, Threo- - L-Norvaline, 3-Methyl-, Threo- - Norvaline, 3-Methyl-, Threo- - Pentanoic Acid, 2-Amino-3-Methyl-, (S-(R*,S*))-