Dipeptide epimerase with a preference for substrates containing a Glu residue in the second position. Catalyzes the epimerization of L-Ala-L-Glu, L-Ser-L-Glu, L-Thr-L-Glu, L-Val-L-Glu, L-Gly-L-Glu and L-Thr-L-Glu (in vitro). May play a role in the metabolism of the murein peptide, of which L-Ala-D-Glu is a component. L-alanyl-L-glutamate = L-alanyl-D-glutamate Binds 1 Mg(2+) ion per subunit. Part of a large, functionally divergent protein family. Protein modeling and substrate docking were used to predict the substrate specificity, prior to biochemical analysis. Belongs to the mandelate racemase/muconate lactonizing enzyme family.