Enzymic Introduction of the Methyl Ester Groups of Pectin

Abstract A particulate preparation obtained from Phaseolus aureus shoots contains an enzyme capable of transferring the 14C-labeled methyl groups from S-adenosyl-l-methionine to the carboxyl groups of polygalacturonic acid, which seems to be present in the same particulate material. The introduction of the methyl ester groups is optimal at pH 6.8 and does not require divalent ions. 5-N-Methyltetrahydrofolate does not act as a donor of methyl groups. The apparent Michaelis constant of the enzyme for S-adenosyl-l-methionine is about 6 x 10-5 m.