309 - Electrostatic and structural properties of the surface of human erythrocytes. I-cell-electrophoretic studies following neuraminidase treatment

Abstract

Following neuraminidase treatment the electrophoretic mobility of human erythrocytes was measured in dependence on the ionic strength. It could be shown that neuraminic acid groups are the only charge carriers within the ranges of the surface coat passed by the electro-osmotic flow. A quantitative comparison of the measured ionic-strength dependences of neuraminidase-treated and non-treated erythrocytes showed a structural change of the surface coat accompanied by charge reduction. The degradation of neuraminic acid led to colayering of the surface coat molecules. The total charge was determined to be 1.8×10 7 negative elementary charges/erythrocyte. In deeper layers of the surface coat there were 2×10 6 negative elementary charges which could not be reduced by neuraminidase. The theoretical concept of the influence of the three-dimensional charge distribution of the cell surface on the electrophoretic mobility [1, 2] could be checked in qualitative and quantitative terms. There was a considerably better correlation of surface charge density to biochemical data than that so far obtained by electrophoretic studies.