Abstract
A pectinesterase (EC 3.1.1.11), responsible for the spontaneous gel-formation of the awkeotsang polygalacturonide, was isolated from the red tepals attached to the pedicels of seeds of Ficus awkeotsang Makino. The methyl esterase, partially purified by ion-exchange column chromatography on Q-Sepharose, showed an optimum pH of 5.4 for its enzyme activity in the absence of potassium or calcium ions, but the pH in the presence of these ions being sifted to 7.0-8.0.
As judged on comparison of the spontaneous gel-formation of the water extract of seeds and the enzyme-induced gel-formation of the polygalacturonide solution by treatment with the awkeotsang pectinesterase, the spontaneous gel-formation of the awkeotsang seed extract must be induced through the action of an intrinsic pectinesterase on the methoxylated linear polygalacturonide and then the formation of the so-called "egg-box" structure, calcium ions being placed between the polygalacturonide chains of the de-esterified α-(1→4)-linked D-galacturonic acid residues.
