Catalyzes the depolymerization of pectins of methyl esterification degree from 13 to 75%, with an endo mode of action. Cannot degrade polygalacturonate. Also displays protopectinase activity, i.e. releases pectin from protopectin. Eliminative cleavage of (1->4)-alpha-D-galacturonan methyl ester to give oligosaccharides with 4-deoxy-6-O-methyl-alpha-D-galact-4-enuronosyl groups at their non-reducing ends. Inhibited by Hg(2+) and Mn(2+). Not affected by EDTA in vitro. Optimum pH is 8.0. Retains 70% of activity after 16 hours incubation in the pH range 4-11, at 37 degrees Celsius. Optimum temperature is 60 degrees Celsius. Retains more than 90% and 70% of activity after 30 min incubation at pH 6 at 50 and 60 degrees Celsius, respectively. Up-regulated under high-phosphate conditions. Does not require calcium for activity. Belongs to the polysaccharide lyase 1 family.