A Simple and Convenient Method for Assaying Pectic Enzyme Activities

Abstract

A simple and convenient assay method for detecting pectic enzymes was devised by using Cetavlon (cetyltrimethylammonium bromide), which forms precipitates with acidic polysaccharides.
Five rnilliliters of 2% agar solution containing 0.3% pectin or pectic acid was poured into petri dishes (9cm in diameter), and stainless cups (8mm in diameter, 10mm in height) which used to assay antibiotic substances were put on the agar plates. Enzyme solution was poured into the cups and incubated for about 15hr at 37°C. For detecting the lytic zones, 3% Cetavlon solution was run into the agar plates, and allowed to standing for about 30min at room temperature. The diameter of lytic zone around the cups was measured with a ruler. There was a linear relationship between the diameter of the lytic zone and logarithms of enzyme concentration. The pH optima of the pectic enzymes were also estimated by changing the pH of the agar plates containing the substrate. Pectic acids with degrees of polymerization below 12 to 15 did not form precipitates with Cetavlon.