Pectic Enzymes

The pectic enzymes that degrade the pectic substances have been found in higher plants and in microorganisms but, other than the snail, are not found in animals. The pectic substances include the galacturonans, the rhamnogalacturons, arabinans, galactans, and arabinogalactans. Pectin has about 75% of its carboxyl groups esterified with methanol. Pectic acid is a compound in which essentially all of the carboxyl groups of the anhydrogalacturonic acid units are free. There are three types of pectic enzymes. The pectic enzyme types are: pectinesterase, the “polygalacturonases” and the pectate lyases. The enzyme has often been referred to as pectase, pectin methoxylase, pectin demethoxylase, pectolipase, and pectin methylesterase. One of the best studied of the pectinesterases is the enzyme from orange albedo. Several methods are available to distinguish between the exo- and endosplitting enzymes. One of the most useful methods is to compare the rate of decrease in viscosity with rate of hydrolysis as measured by increase in reducing groups.