Catalyzes the dehydration of glucarate to 5-keto-4-deoxy-D-glucarate (5-kdGluc). D-glucarate = 5-dehydro-4-deoxy-D-glucarate + H2O Carbohydrate acid metabolism; D-glucarate degradation; 2,5-dioxopentanoate from D-glucarate: step 1/2. Belongs to the mandelate racemase/muconate lactonizing enzyme family. GlucD subfamily.