Alanine racemase, C-terminal <p>Alanine racemase (<db_xref db="EC" dbkey="5.1.1.1"/>) plays a role in providing the D-alanine required for cell wall biosynthesis by isomerising L-alanine to D-alanine. Proteins contains this domain are found in both prokaryotic and eukaryotic proteins [<cite idref="PUB00006264"/>,<cite idref="PUB00006317"/>]. The molecular structure of alanine racemase from <taxon tax_id="1422">Bacillus stearothermophilus</taxon> (Geobacillus stearothermophilus) was determined by X-ray crystallography to a resolution of 1.9 A [<cite idref="PUB00000440"/>]. 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-strand. 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.</p>