Acts in the modification of cell walls via demethylesterification of cell wall pectin (PubMed:18936961). Acts in a blockwise manner, resulting in a cell wall rigidification. [(1->4)-alpha-D-galacturonosyl methyl ester](n) + n H2O = [(1->4)-alpha-D-galacturonosyl](n) + n H(+) + n methanol Does not require salt for activity. Not inhibited by kiwi pectin methylesterase inhibitor (PMEI). Optimum pH is 8.0-8.5. Fully active at 0 or 30 degrees Celsius, inactive at 55 degrees Celsius. 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. This is the only member of the pectinesterase family that do not contain a transmembrane or a signal peptide. Belongs to the pectinesterase family.