Involved in the degradation of pectin. May assist in the removal and modification of an existing pectin matrix in order to allow the deposition of newly synthesized walls polymers for a specialized function or to create an architecture that is extensible. Eliminative cleavage of (1->4)-alpha-D-galacturonan to give oligosaccharides with 4-deoxy-alpha-D-galact-4-enuronosyl groups at their non-reducing ends. Binds 1 Ca(2+) ion. Required for its activity. Optimum pH is 10. Glycan metabolism; pectin degradation; 2-dehydro-3-deoxy-D-gluconate from pectin: step 2/5. Expressed in sites of vascular differentiation and in new primordia on the flank of the shoot meristem. Up-regulated by auxin. Belongs to the polysaccharide lyase 1 family.