Changes in the Conformation and Distribution of Hemoglobin in the Erythrocyte upon Inhibition of Na + /K + -ATPase Activity

Raman spectroscopy, infrared spectroscopy and laser interference microscopy revealed both morphological changes and changes in the conformation of hemoglobin in the erythrocyte as a result of an increase in the ratio of [Na + ] in and [K + ] in when cellular Na + /K + -ATPase was inhibited. It was found that the Na + /K + -ATPase inhibition led not only to an increase in [Na + ] in in the cell, it also increased the positive charge on the cytoplasmic surface of the plasma membrane. Under these conditions, changes in the conformation of both heme and the protein globule of hemoglobin were detected, namely there was a decrease in the packing density of the hemoglobin molecule, which could be associated with both the sorption of Na + (or Ca 2+ ) with hemoglobin, and with an increase in the number of water molecules in the cell and the redistribution of hemoglobin. It is likely that the redistribution of hemoglobin and the change in the packing density of globin affected the conformation of heme; this increased the probability of hemoglobin heme to be in a “dome-shaped form” and, thus, increased its ability to bind O 2 .