Contributes significantly to bacterial utilization of polygalacturonate and the induction of pectate lyase in the presence of extracellular pectic polymers. [(1->4)-alpha-D-galacturonosyl](n) + H2O = [(1->4)-alpha-D-galacturonosyl](n-2) + alpha-D-galacturonosyl-(1->4)-D-galacturonate Belongs to the glycosyl hydrolase 28 family.