Involved in degradation of pectin, which causes soft-rod disease in plants. 4-(4-deoxy-alpha-D-galact-4-enuronosyl)-D-galacturonate = 2 5-dehydro-4-deoxy-D-glucuronate Glycan metabolism; pectin degradation; 2-dehydro-3-deoxy-D-gluconate from pectin: step 3/5.