Enzymatic Maceration of Plant Tissues by Endo-Pectin Lyase and Endo-Polygalacturonase from Aspergillus japonicus

Abstract

A. japonicus produces endo-pectin lyase and endo-polygalacturonase as the main pectin depolymerases. The 2 enzymes differed in ability to macerate tissues of different plant species. Endo-pectin lyase most rapidly macerated onion tissues, while endo-polygalacturonase was most effective on radish tissue. Potato tissues were similarly macerated by the 2 enzymes. Susceptibility of plant tissues to maceration by the enzymes may depend largely on the enzyme specificity but not enzyme concentration. There were also differences between the 2 enzymes in the effect of pH and Ca2+ on macerating activity. The 2 enzymes apparently differed in ability to release pectic substances from plant cell walls. The pectic substances extractable with 0.05 N NaOH, which are commonly referred to as protopectins, were accessible to endo-pectin lyase, while those extractable with 0.5% ammonium oxalate were accessible to endo-polygalacturonase. The relationship between the susceptibility of plant tissue to maceration by the 2 enzymes and the susceptibility of each pectic substance in the cell wall to attack by the enzymes may suggest the type of pectic substance that is important in cell wall cementing.