EVIDENCE FOR THE PECTIC NATURE OF THE MIDDLE LAMELLA OF POTATO TUBER CELL WALLS BASED ON CHROMATOGRAPHY OF MACERATING ENZYMES

Chromatography of fungal enzyme mixtures on cellulose phosphate columns using pH‐gradient clution was followed by analysis of the separated fractions for polygalacturonase, maceration of killed potato tuber slices, and, in some instances, for pectin transeliminase and cellulase. The peaks of maceration activity coincided with those of endo‐polygalacturonase and pectin transeliminase. The latter was confirmed by further separation on DEAE‐cellulose. Exo‐polygalacturonase appeared not to macerate, and no indication was obtained of maceration by several other polysaccharases known to be present, although they might be demonstrable in the absence of polygalacturonase. These results strongly suggest that the middle lamella of the cell walls of this tissue consist essentially of pectinate (partly esterified polygalacturonate).