The structure of alanine racemase from Staphylococcus aureus subsp. aureus COL was determined by X-ray crystallography to a resolution of 2.37 A. The alanine racemase monomer is composed of two domains, an eight-stranded alpha/beta barrel at the N-terminus, which includes residues 1-245, and a C-terminal beta-stranded domain composed of residues 246-382. Protein is dimeric in the crystal with both domains of each chain being involved in dimerization. The N-terminal domain shall bind pyridoxal 5'-phosphate (PLP) cofactor. In the current apo-structure of IDP00688, there is a phosphate ion per each active site that binds at the same place where phosphate group of PLP is positioned in a homologous alanine racemase from Bacillus stearothermophilus (PDB ID 1SFT). Both proteins share about 43 % sequence identity and have 1.5 A rmsd in the position of their C-alpha atoms.