Exo- and Endo-PGs utilize different hydrolytic modes of action. Endo-PGs hydrolyze in a random fashion along the polygalacturonan network. This method results in oligogalacturonides.[12] Exo-PGs hydrolyze at the non-reducing end of the polymer, generating a monosaccharide galacturonic acid. Occasionally, organisms employ both methods. In addition to different modes of action, PG polymorphism allows fungal PGs to more effectively degrade a wider range of plant tissues. PG variety in optimal pH, substrate specificity, and other factors are likely helpful for pytopathogenic organisms like fungi.[4] wiki