Acts in the modification of cell walls via demethylesterification of cell wall pectin. [(1->4)-alpha-D-galacturonosyl methyl ester](n) + n H2O = [(1->4)-alpha-D-galacturonosyl](n) + n H(+) + n methanol Glycan metabolism; pectin degradation; 2-dehydro-3-deoxy-D-gluconate from pectin: step 1/5. Expressed in siliques. Expressed during late developmental phases of siliques. Belongs to the pectinesterase family.