InterPro domain: IPR001608

Alanine racemase plays a role in providing the D-alanine required for cell wall biosynthesis by isomerising L-alanine to D-alanine.

The molecular structure of alanine racemase from Bacillus stearothermophilus was determined by X-ray crystallography to a resolution of 1.9 A [ 1 ]. The alanine racemase monomer is composed of two domains, an eight-stranded alpha/beta barrel at the N terminus, and a C-terminal domain essentially composed of beta-strands. The pyridoxal 5'-phosphate (PLP) cofactor lies in and above the mouth of the alpha/beta barrel and is covalently linked via an aldimine linkage to a lysine residue, which is at the C terminus of the first beta-strand of the alpha/beta barrel.

This N-terminal domain is also found in the PROSC (proline synthetase co-transcribed bacterial homologue) family of proteins, which are not known to have alanine racemase activity.

1. Determination of the structure of alanine racemase from Bacillus stearothermophilus at 1.9-A resolution. Biochemistry 36, 1329-42