Converts 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC) to 2-succinylbenzoate (OSB) (PubMed:16584181). Also acts as a N-succinylamino acid racemase (NSAR) that catalyzes the racemization of various N-succinylamino acids, including N-succinyl-L-valine, N-succinyl-L-alanine, N-succinyl-L-methionine, N-succinyl-L-tyrosine, N-succinyl-L-serine, N-succinyl-L-isoleucine, N-succinyl-L-phenylalanine and N-succinyl-L-leucine (PubMed:16584181). May be a bifunctional enzyme involved in menaquinone biosynthesis and in an irreversible pathway for the conversion of D- to L-amino acids, thereby facilitating the survival and/or growth of the organism (PubMed:16584181). (1R,6R)-6-hydroxy-2-succinyl-cyclohexa-2,4-diene-1-carboxylate = 2-succinylbenzoate + H2O kcat is 180 sec(-1) with SHCHC as substrate. kcat is 92 sec(-1) with N-succinyl-L-valine as substrate. kcat is 89 sec(-1) with N-succinyl-L-alanine as substrate. kcat is 53 sec(-1) with N-succinyl-L-methionine as substrate. kcat is 52 sec(-1) with N-succinyl-L-tyrosine as substrate. kcat is 45 sec(-1) with N-succinyl-L-serine as substrate. kcat is 35 sec(-1) with N-succinyl-L-isoleucine as substrate. kcat is 19 sec(-1) with N-succinyl-L-phenylalanine as substrate. kcat is 17 sec(-1) with N-succinyl-L-leucine as substrate. Quinol/quinone metabolism; 1,4-dihydroxy-2-naphthoate biosynthesis; 1,4-dihydroxy-2-naphthoate from chorismate: step 4/7. Quinol/quinone metabolism; menaquinone biosynthesis. Belongs to the mandelate racemase/muconate lactonizing enzyme family. MenC type 2 subfamily.