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The sorption of nonpenetrating vital phthalocyanine dye--Heliogen Blue (HB) into the cells was studied on the human red cells incubated in hypertonic, isotonic and hypotonic solutions. The alteration in the outer membrane surface was detected using the monomer-dimer ratio (M/D) deduced from the absorbtion spectra of the sorbed dye, and the concentration (C) of the dye in membrane. The decrease in M/D and C was found in hypotonic and hypertonic conditions, resp. The increase in the number of binding sites caused by conformational changes in membrane is discussed.

The absorption spectra of Heliogen Blue (HB) dye were registered on stained ghosts of human red blood cells. The monomer-dimer ratio (M/D) was used as a characteristic of the absorbtion band of HB in the red spectral region. It is determined that incubation of ghosts in the sodium hydrate solution (pH 12) leads to changes in the visible HB spectrum. When the ghosts are stained after NaOH treatment, the M/D value decreases. When stained ghosts are treated with NaOH, the M/D value increases. The decrease in M/D value is due to the increase in HB sorption capacity of the modified membranes; the increase in M/D value is due to the removal of proteins sorbing HB. The appearance of additional sites for HB sorption and the decrease in M/D value in the HB spectrum may be explained by a conformational alteration of the integral proteins or by substitution of some molecules of the peripheral proteins for the HB molecules.

The sorption of vital phthalocyanine dye--Heliogen Blue (HB)--by red cells and their ghosts after trypsin treatment has been studied. The structural alteration in the outer and inner surface of the membrane was detected using the monomer-dimer ratio (M/D) deduced from the absorption spectra of the sorbed dye. The trypsin treatment causes the increase in the M/D ratio. It is greater (44%) when both the membrane surfaces are exposed to trypsin (unsealed ghosts), and is only 19% when the whole erythrocytes are treated. The similar alteration (M/D increased by 18%) is obtained for red blood cells stained after incubation in the isotonic buffer solution at 37 degrees C. Recent findings show a good agreement with our previous data on the influence of changes in the membrane surface on the value of the M/D ratio. A possibility of using HB in determination of structural changes of a native membrane is discussed.

Human intact erythrocytes and their ghosts (resealed and unresealed) were stained by the vital dye Heliogen Blue, which does not penetrate the cell being only sorbed by its membrane. The absorption spectra of the sorbed dye were examined. On the external surface of the membrane, the molecular (monomer) state of dye sorption is revealed, whereas on the interior side the dye sorption is mostly in the polymolecular (dimer) state. The differences in staining can be evaluated by the monomer-dimer ratio (M/D), which may be used for comparison between the sorption characteristics of membrane preparations.