Polygalacturonase (EC 3.2.1.15, pectin depolymerase, pectinase, endopolygalacturonase, pectolase, pectin hydrolase, pectin polygalacturonase, endo-polygalacturonase, poly-alpha-1,4-galacturonide glycanohydrolase, endogalacturonase, endo-D-galacturonase, poly(1,4-alpha-D-galacturonide) glycanohydrolase, PG) is an enzyme produced in plants which is involved in the ripening process, and by some bacteria and fungi which are involved in the rotting process. PGs degrades polygalacturonan present in the cell walls of plants by hydrolysis of the glycosidic bonds that link galacturonic acid residues. Polygalacturonan is a significant carbohydrate component of the pectin network that comprises plant cell walls. The activity of the endogenous plant PGs work to soften and sweeten fruit during the ripening process. Similarly, phytopathogens use PGs as a means to weaken the pectin network, so that a host of digestive enzymes can be excreted into the plant host to acquire nutrients.