Also known as MENH_SALTY, menH. Catalyzes a proton abstraction reaction that results in 2, 5-elimination of pyruvate from 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate (SEPHCHC) and the formation of 2-succinyl-6-hydroxy-2, 4-cyclohexadiene-1-carboxylate (SHCHC). Monomer.