Abraham Rosenberg

Biological roles of sialic acid

1 Chemistry and Analysis of Sialic Acid.- I. Historical Background.- II. Natural Occurrence of Sialic Acids.- III. Isolation and Purification.- IV. Chemistry of Sialic Acids.- A. Basic Structures.- B. Stereochemistry.- C. Chemical Reactions and Derivatives.- V. Synthesis.- VI. Quantification of Sialic Acids.- A. Colorimetric and Fluorometric Assays.- B. Enzymatic Assay.- C. Gas-Liquid Chromatography.- VII. References.- 2 The Natural Occurrence of Sialic Acids.- I. Introduction.- II. The Natural Occurrence of Sialic Acids.- A. Viruses.- B. Bacteria.- C. Plants.- D. Invertebrates.- E. Primitive Chordates.- F. Vertebrates.- III. Evolution of Sialic Acids.- IV. References.- 3 The Distribution of Sialic Acids Within the Eukaryotic Cell.- I. Introduction.- II. Extracellular Sialic Acids.- III. Distribution within the Cell.- A. The Plasma Membrane.- B. Endoplasmic Reticulum.- C. Mitochondria.- D. Nuclei.- E. Other Fractions.- IV. Conclusions.- V. References.- 4 Anabolic Reactions Involving Sialic Acids.- I. Introduction: Perspective and Directions.- II. Biosynthesis of the Sialic Acids.- A. Glucose to Sialic Acid.- B. Activation.- C. Regulatory Problems.- D. Other Derivatizations.- III. Biosynthesis of Polymers, Glycoproteins, Mucins, and Glycolipids Containing Sialic Acid.- A. Colominic Acid Synthesis.- B. CMP-Sialic Acid: Lactose (?-Galactosyl) Sialyltransferase.- C. CMP-Sialic Acid: Glycoprotein (?-Galactosyl) Sialyltransferases.- D. CMP-Sialic Acid: Mucin (?-N-Acetylgalactosaminyl) Sialyltransferase.- E. CMP-Sialic Acid: Ganglioside (Glycolipid) Sialyltransferases.- IV. Thoughts on Physiological Function of Sialic Acids.- V. References.- 5 Catabolism of Sialyl Compounds in Nature.- I. Introduction.- II. Pathways of Degradation.- A. Degradation of Gangliosides.- B. Degradation of Glycoproteins.- III. Cellular Mechanism of Degradation.- A. Lysosomes.- B. Uptake and Disposition of Substrates.- IV. Functional Implications.- V. Concluding Remarks.- VI. References.- 6 Disorders of Ganglioside Catabolism.- I. Introduction-The Catabolism of Gangliosides.- II. Tay-Sachs Disease (Type I GM2-Gangliosidosis).- A. Clinical Aspects.- B. Pathology.- C. Chemistry of the Storage Material.- D. Nature of the Metabolic Defect.- E. Enzymology of Type I GM2-Gangliosidosis.- F. Prenatal Diagnosis and Treatment.- III. Type II GM2-Gangliosidosis.- A. Clinical and Pathological Aspects.- B. Chemistry of the Storage Material.- C. Metabolic Defect-Diagnosis and Treatment.- IV. Other Variant Forms.- A. Type III GM2-Gangliosidosis.- B. Hexosaminidase-A-Deficient Adults.- V. Generalized Gangliosidosis (GM1-Gangliosidosis).- A. Clinical Aspects.- B. Pathology.- C. Chemistry of the Stored Material.- D. Metabolic Defect.- VI. Potentially Related Disorders.- A. Hematoside (GM3)-Gangliosidosis.- B. Animal Model Gangliosidoses.- C. In Vitro Model Studies.- VII. References.- 7 The Biological Role of Sialic Acid at the Surface of the Cell.- I. Introduction.- II. Occurrence, Forms, and Amounts of Sialic Acid Residues at the Surface of the Cell.- III. The Masking of Cell-Surface Antigens by Sialic Acid.- IV. Sialic Acid as a Receptor at Cell Surfaces.- A. Receptor for Lectins.- B. Receptor for Viruses.- C. Receptor for Mycoplasma.- D. Receptor for Hormones.- E. Receptor for Antibodies.- F. Receptor for Circulating Glycoproteins.- G. Receptor for Tetanus Toxin.- V. Sialic Acid in Normal and Malignant or Transformed Cells.- VI. Role of Sialic Acid in Cell-to-Cell Interaction.- A. Cellular Adhesion.- B. Intercellular Aggregation.- C. Agglutination.- VII. Physiological Role of Sialic Acid Residues.- A. Transport of Ions, Amino Acids, and Proteins.- B. Phagocytosis.- C. Anaphylactic Shock, Hypercapnia, and Brain Excitability.- D. Lymphocyte Stimulation.- E. Sperm Capacitation.- VIII. Conclusion.- IX. References.- 8 The Altered Metabolism of Sialic-Acid-Containing Compounds in Tumorigenic-Virus-Transformed Cells.- I. Introduction.- II. Experimental Procedures.- A. Cells and Cell Culture.- B. Isolation, Identification, and Quantification of Gangliosides.- C. Assay of Enzymes Involved in Glycolipid Metabolism.- III. Ganglioside Metabolism in Cultured Mouse Cell Lines.- A. Distribution of Gangliosides in Normal and Virally Transformed Cells.- B. Enzymatic Studies.- C. Effect of Growth and Culture Conditions on Ganglioside Metabolism.- D. Sialic-Acid-Containing Glycolipids in Transformed Cells Obtained from Other Species.- VI. Sialic Acid and Glycoproteins in Transformed Cells.- A. Sialic Acid and Sialyltransferase Activity in Transformed Cells.- B. Membrane Glycoproteins.- C. Glycopeptides of Transformed Cells.- D. Role of Sialic Acid and Sialyltransferase.- E. Comments.- V. Relationship between Viral Transformation and Altered Ganglioside Metabolism.- A. Productive Infection of Mouse Cells.- B. Ganglioside Metabolism in Flat Revertant Cell Lines.- C. Specificity of the Altered Ganglioside Metabolism.- D. Generality of the Phenomenon.- E. Transformation of Mouse Cells by RNA Tumor Viruses and Other Agents.- VI. Discussion.- A. Molecular Basis of Altered Ganglioside Metabolism.- B. Significance.- VII. Concluding Remarks.- VIII. References.- 9 Circulating Sialyl Compounds.- I. Introduction.- II. Normal Plasma Constituents.- A. Circulating Sialoenzymes.- B. Serum Sialoglobulins.- C. Sialoglycoprotein Hormones.- III. Circulating Sialoglycoproteins in Abnormal Physiological States.- A. Diabetes.- B. Inflammatory Reactions.- C. Infectious Psychoses.- D. The Effect of Steroid Hormones.- E. Liver Disease.- F. Virus Inhibition of Hemagglutination.- G. Cancer.- H. Diet.- IV. Role of Sialic Acid in Circulating Sialoglycocompounds.- V. References.- 10 Sialidases.- I. Background and Nomenclature.- II. Bacterial Sialidases.- A. Occurrence of Microbial Sialidases.- B. Organismic Characterization and Induction of Bacterial Sialidases.- C. Purification of Bacterial Sialidases.- D. Size and Properties of Bacterial Sialidases.- E. Mode of Action of Bacterial Sialidases.- F. Biological Roles for Bacterial Sialidases.- III. Viral Sialidases.- A. Morphology and Genetics of Viral Sialidases.- B. Purification of Viral Sialidases.- C. Size of Viral Sialidases.- D. Properties of Viral Sialidases.- E. Possible Biological Roles for Viral Sialidases.- IV. Experimental Use of Microbial Sialidases.- V. Mammalian Sialidases.- A. Organ Distribution of Mammalian Sialidases.- B. Subcellular Distribution of Mammalian Sialidases.- C. Purification of Mammalian Sialidases.- D. Assay of Mammalian Sialidases.- E. Physical Properties of Mammalian Sialidases.- F. Developmental Studies of Mammalian Sialidases.- G. Possible Biological Roles of Mammalian Sialidases.- H. Sialidase Activity in Cells in Tissue Culture.- VI. References.

Lack of evidence for the involvement of a β-D-galactosyl-specific lectin in the fusion of chick myoblasts

Abstract The role of a β-D-galactosyl-specific lectin, first reported by Teichberg et al. , in the fusion of myoblasts in vitro was investigated. The concentration of this lectin in embryonic chick skeletal muscle was found to reach maximal levels at the time of myoblast fusion in vivo . β-D-Galactosyl-β-thiogalactopyranoside and lactose are potent inhibitors of agglutination of trypsinized rabbit erythrocytes caused by the lectin. However, at concentrations of 50 mM these compounds had no effect on either nonsynchronous fusion of myoblasts or on the release of synchronized myoblast cultures from EGTA fusion block. The presence of the agglutinin in the external membranes of chick myoblasts and myotubes could not be demonstrated. It is, therefore, concluded that the involvement of the lectin in the fusion of chick myoblasts remains questionable.

The Organization of Gangliosides and Other Lipid Components in Synaptosomal Plasma Membranes and Modifying Effects of Calcium Ion

Synaptosomes were prepared from bovine brain by zonal rotor sucrose density centrifugation. While a major fraction of lipid-bound sialic acid is included uniformly within the synaptosomal distribution profile, the sialoglycoproteins and some gangliosides do not follow this pattern, Exposure to extrasynaptosomal calcium results in alterations in the surface labeling properties of some gangliosides and membrane plasmalogens, suggesting that extrasynaptic Ca2+ may influence the conformation of complex lipids in synaptic plasma membranes. The level of intrinsic membrane-associated sialidase activity that liberates sialic acid from these sialoglycoconjugates parallels the synaptosomal buoyant density distribution profile, supporting a view that this enzyme resides in synaptosomal membranes in close association with a sialolipid substrate.

Interaction of triiodide anion with gangliosides in aqueous iodine

Abstract Molecular iodine interacts with the anionic, sialic acid-containing glycosphingolipid, ganglioside, to produce triiodide anion. The “triiodide” spectrum arising from the interaction, with absorption maxima at 287 nm and 351 nm, apparently is identical with that given by sodium iodide-iodine solutions, and it is destroyed by addition of sodium thiosulfate. The interaction has been applied to an estimation of the aggregative properties of the lipid in aqueous medium in terms of the critical micelle concentration (CMC). The following CMCs were determined: Tay-Sachs ganglioside, 7.5 × 10−5 M; monosialoganglioside, 8.5 × 10−5 M; disialoganglioside, 9.5 × 10−5 M; trisialoganglioside, 1 × 10−4 M. Absorption maxima of the triiodide spectrum are the same above or below the CMC, and no change is induced by heating to 65°C. The interaction of iodine and gangliosides produces a greater molecular ratio of triiodide ion relative to ganglioside below the CMC than above. This finding is interpreted to indicate a less anionically shielded submicellar, as compared with micellar, interior for ganglioside aggregates. The lack of dependence of the triiodide absorption maxima on the degree of aggregation of ganglioside molecules is proposed to stem from a cavitation structure for the associated molecules in which the micellar interior is subject to considerable water penetration. Triiodide anion is clearly associated with ganglioside aggregates as evidenced by coprecipitation of the triiodide anion with ganglioside micelles upon ultracentrifugation.

Large-scale preparation of synaptosomes from bovine brain using a zonal rotor technique

A zonal rotor technique for the preparation of synaptosomes in bulk from bovine brain frontal cortex based on an empirical transformation of a small-volume discontinuous surcrose density gradient arrangement is presented in detail. The procedure yields new information concerning synaptosomes prepared in sucrose gradients. Cerebroside analysis and electron microscopy show myelin contamination to be restricted to the leading, less dense edge of the synaptosomal profile, free mitochondria to the trailing, more dense edge. Exclusion of fringe areas yields a highly purified synaptosome preparation which entirely enters the next dense layer beyond the 0.8∶1.2 M sucrose interface. This interface collects most of the oubain-sensitive (Na+, K+) adenosine triphosphatase activity. The purified synaptosomes display very high intrinsic sialidase activity and are rich in di-, tri-, and tetrasialogangliosides, the preferred substrates for the enzyme. Up to 90% of the cholinesterase activity in the zonal rotor synaptosome preparation is specific acetylcholinesterase.

Effect of cellular desialylation on choline high affinity uptake and ecto-acetylcholinesterase activity of cholinergic neuroblasts.

Abstract It is not definitely established whether choline can be synthesized by nerve tissue (1,2). Its uptake by the neuronal membrane may be an important regulator of neuronal phosphatidylcholine and acetylcholine metabolism. An energy-dependent component of the choline uptake system has recently been found in neuroblastoma cell cultures (3). Choline uptake in cholinergic neuroblasts is markedly reduced by inhibition of cholinesterase activity (4). Further information about the system for choline transport still is lacking. To gain insight into the biochemical mechanism(s) at the cell surface which are involved in choline uptake by nerve cells, cultured cholinergic neuroblasts in the present study were subjected to gentle sialidase treatment, and choline uptake and acetylcholinesterase activities (AChE, EC 3.1.1.7) were determined in parallel. Removal of a portion of the cell surface sialic acid markedly reduced choline uptake and concurrently enhanced AChE activity. These findings suggest an interrelatedness of choline uptake and acetylcholinesterase activity mediated by sialic acid components in the outer surface of the cell.

Biosynthesis and Metabolism of Gangliosides

It is pertinent to an understanding of the metabolism of brain gangliosides to consider their concentration and their more or less specific location within neural cells. The CNS of vertebrates characteristically has a relatively high level of gangliosides (Wiegandt, 1968; Brunngraber et al., 1972). Those gangliosides containing the more highly sialylated (tri- and tetrasialosyl) ganglio- tetraoses, e.g., II3(NeuAc)3-GgOse4Cer, or GTIc; IV3(NeuAc)II3(NeuAc)2- GgOse4Cer, or GTlb; IV3(NeuAc)2II3(NeuAc)2-GgOse4 Cer, or GQlb, appear to occur specifically in the brain of animals, and additionally, those containing IV3(NeuAc)2 II3(NeuAc)3-GgOse4Cer, or GPlc, are found in fish brain (Avrova, 1971). Sialosyl gangliotetraosyl ceramides also occur to a varying degree in cellular membranes in organs other than brain. Sialosyl lactosyl and gangliotriaosyl ceramides (Gm3 and Gm2) occur largely in nonneural as well as neural cells. For a discussion of the structures and distribution of the (“brain”) gangliosides, see Chapter 1.

Sialidase activity of oncogenic cells transformed by herpes simplex virus

Abstract Sialidase in normal nononcogenic hamster embryo fibroblasts was not active toward added disialo- and trisialoganglioside, but all transformed lines of hamster embryo fibroblasts studied had sialidase active toward added ganglioside substrate. The levels of exogenous sialidase activity suggested a parallel trend in the amount of this activity and the degree of oncogenicity of the transformed cells. Exogenous sialidase activity in a weakly oncogenic cell line was found to increase after passage of the cells into hamsters and isolation and cell culture of the resulting tumors which gave rise to a cell line of relatively high oncogenicity.

Light-independent stoichometry of galactosyl diglyceride and chlorophyll accretion during light-induced chloroplast membrane synthesis in Euglena.

In photobiotic Euglena gracilis, chlorophyll biosynthesis takes place at a rate which is a direct function of light intensity. There is stoichiometry between chlorophyll accumulation and that of galactosyl diglycerides. This stoichiometry remains relatively invariant, regardless of the wide changes in chlorophyll content brought about in response to controlled variation of light intensity. These findings suggest that the formation of chlorophyll-containing photoreceptor membranes may be paced and stabilized by concurrent synthesis of galactosyl diglycerides.

Action of Rat Brain Sialidase on Synaptic Membrane Components in Situ

To provide further information on the characteristics of synaptic membrane sialidase, leading to some understanding of its biological role, we have examined the susceptibility of intrinsic sialo compounds of the synaptosomal membrane to the action of synaptic membrane sialidase in situ. Sialo compounds were labeled in vivo by the intracranial injection of radioactive N-acetylmannosamine during rapid synaptogenesis in rats (1) which is marked by ganglioside synthesis (2) and appearance of electrophysiological function (3). The high levels of sialo compounds and sialidase in mammalian nerve ending membranes lend importance to an understanding of their metabolism. Specific radioactive labeling has permitted sensitive and accurate observation of the behavior of intrinsic synaptic membrane sialidase and the various sialic acid-containing components.