Through pore diameter in the cell wall of Chara corallina

Determination of pore size of the cell wail of Chara corallina has been mad e by using the polyethylene glycol (PEG) series as the hydrophilic probing molecules, In these experiments, the polydispersity of commercial preparati on of PEGs was allowed for, The mass share (gamma (p)) of polyethylene glyc ol preparation fractions penetrating through the pores was determined using a cellular 'ghost', i.e. fragments of internodal cell walls filled with a 25% solution of nonpenetrating PEG 6000 and tied up at the ends. In water, such a 'ghost' developed a hydrostatic pressure close to the cell turgor wh ich persisted for several days. The determination of gamma (p), for polydis perse polyethylene glycols with different average molecular mass ((M) over bar) was calculated from the degree of pressure restoration after water was replaced by a 5-10% polymer solution. Pressure was recorded using a dynamo meter, which measures, in the quasi-isometric mode, the force necessary for the partial compression of the 'ghost' in its small fragment. By utilizing the data on the distribution of PEG 1000, 1450, 2000, and 3350 fractions o ver molecular mass (M), it was found that gamma (p), for these polyethylene glycols corresponded to the upper limit of M-L=800-1100 D (hydrodynamic ra dius of molecules, r(h) = 0.85-1.05 nm), Thus, the effective diameter of th e pores in the cell wall of Chara did not exceed 2.1 nm.