3-Hydroxyaspartic acid (three letter abbreviation: Hya) also known as beta-hydroxyaspartic acid is derivative of aspartic acid which has been hydroxylated at position-3.

The adjacent image shows L-threo-3-Hydroxyaspartate.

Similarly to proteinogenic isoleucine and threonine, 3-hydroxyaspartic acid contains two chiral centers.

As such, it can exist in 4 stereoisomers, which form two pairs of enantiomers.

The Hya amino acid residue is sometimes contained in EGF-like domains such as Vitamin K-dependent coagulation plasma proteins including protein C.[1] D-threo-3-Hydroxyaspartate is a part of the siderophore ornibactin.