Solubilization of pectic polysaccharides from the cell walls of Lemna minor and Apium graveolens

The kinetics of solubilization of pectic polysaccharides from purified cell walls of Lemna minor (duckweed) and Apium graveolens (celery) by ammonium oxalate at 22 degrees was determined. With cell walls of L, minor, 30 +/- 1 (average of three experiments, average deviation from the mean) and 34 +/- 1% of the total anhydrouronic acid of the cell walls was solubilized in 15 min and 5 hr, respectively. Water at 22 degrees solubilized 1.3 +/- 0.2% and 1.3 +/- 0.4% of the total anhydrouronic acid in 15 min and 5 hr, respectively. With cell walls of A. graveolens, 19 +/- 1% (average of two experiments, average deviation from the mean) and 23 +/- 1% of the total anhydrouronic acid of the cell wall was solubilized in 15 min and 3 hr, respectively. Water at 220 solubilized 0.9 +/- 0.6 and 0.9 +/- 0.1% of the total anhydrouronic acid in 15 min and 3 hr, respectively. When trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid was the extractant, recovery values based on weight for the soluble pectic polysaccharide fractions were incorrect (high). Color formation in the uronic acid test was inhibited by sodium dodecyl sulfate. A rapid, two-step procedure for isolating purified cell walls was developed.