[Spectrophotometric study of intact and trypsin-treated erythrocyte membranes using a phthalocyanine dye]

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.