Sialic Acids and the Electrokinetic Charge of the Human Erythrocyte

Effects of modification of the membranes of intact erythrocytes on the anti‐haemolytic action of chlorpromazine

“…The two enzymes added together released only a little more than neuraminidase alone (0.5 + 0.03 ,imol/ml packed cells), indicating that the sialic acids were released by both enzymes from almost the same sites. On the assumption (Cook et al, 1961) osmotic fragility curves were the same at and around 50% haemolysis (Figure 2). …”

“…The enzymes used were neuraminidase which specifically removes terminal sialic acid residues from membrane glycoprotein and trypsin which removes these sialic acids together with some peptide fragments (Cook, Heard & Seaman, 1961).…”

Agglutination by polylysine of young and old red blood cells

“…Gottschalk and Lind (ref 8) demonstrated that the substrate of the RDE on the red cell surface was neuraminic acid. Cook, Heard, and Seaman (ref 9) have shown that there is a reduction in electrophoretic mobility after treatment of red cells with neuraminidase. Glaeser and Mel (ref 10) have recently demonstrated by different methods that the negative charge on the red cell surface can be almost wholly ascribed to the carboxylic group of neuraminic acid.…”

Loss of Sperm Surface Sialic Acid Induces Phagocytosis: An Assay with a Monoclonal Antibody T21, Which Recognizes a 54K Sialoglycoprotein

“…In general, cell surface negative charge is chiefly due to sialic acid residues [7,17,281, and the bound sialic acid residues have significant biological functions, such as masking of antigens (anti-recognition) and cell-cell recognition in some cells [24,27,281. In the epididymis, sialic acid residues are reported to be secreted by the epithelium as a terminal sugar of sialoglycoproteins and bound to sperm surface [ l , 6, 12-14, 18, 23, 25, 35, 36, 381.…”

“…These secretory products of the epididymis are believed to be involved in the changes that spermatozoa undergo during maturation which causes them to gain functions essential for fertilizing ability such as zona pellucida binding and forward motility [3,4, 401. In general, cell surface negative charge is chiefly due to sialic acid residues [7,17, 281, and the bound sialic acid residues have significant biological functions, such as masking of antigens (anti-recognition) and cell-cell recognition in some cells [24,27, 281. In the epididymis, sialic acid residues are reported to be secreted by the epithelium as a terminal sugar of sialoglycoproteins and bound to sperm surface [ l , 6, 12-14, 18, 23, 25, 35, 36, 381.…”