ENTRAPMENT OF DEXTRAN IN PLANT-CELL CAPSULES BY REVERSIBLE CHANGE OF CELL-WALL PERMEABILITY

Vesicular packing material (VP) made of clusters of extracted higher p lant cells with the intact framework of their cell wall was used so fa r for permeation chromatography (vesicle chromatography). The objectiv e of this study was to devise a method to entrap dextran in the vesicl es. This can provide a means to entrap biocatalysts and secondly, to c reate aqueous two-phase systems with a stationary dextran phase for li quid-liquid partition chromatography. Dextran of molecular sizes above the separation limit of the plant cell wall cannot permeate into the intracellular space in aqueous medium. However, in hydrophilic organic solvent/water mixtures, dextran molecules can diffuse into the capsul es. The removal of the organic solvent leaves the dextran trapped insi de. There was an inverse correlation between the percentage of dextran permeating through the cell wall (P(perm)) and the concentration of s olvent required for dextran precipitation. The increase of permeabilit y is therefore considered to be caused, to a great extent, by the decr ease of the effective size of dextran molecules due to decreased solva tion. P(perm) was inversely correlated to the dielectric constants and the polarities of the solvents and, in the case of protic solvents, t he hydrogen-bond acidities. No correlation was found to the hydrogen-b ond basicities.