A detailed study of the periodate oxidation of sialic acids in glycoproteins.
TL;DR: Periodate oxidation of terminalN-acetyl- andN-glycoloylneuraminic acid residues in the mucins from edible bird nest substance and pig submandibular gland can be carried out under conditions which exclusively give rise to the formation of the C-7 analogues of these sialic acids.
Abstract: Periodate oxidation of terminalN-acetyl- andN-glycoloylneuraminic acid residues in the mucins from edible bird nest substance and pig submandibular gland, respectively, can be carried out under conditions which exclusively give rise to the formation of the C-7 analogues of these sialic acids. In contrast, the C-8 compounds can be obtained in a maximum yield of about 40%. Under identical conditions,N-glycoloylneuraminic acid is oxidized about 1.5 times faster than theN-acetylated derivative. After release of the sialic acids by acid hydrolysis, the characterization of the oxidation products was carried out by TLC, by GLC and GLC-MS of the corresponding pertrimethylsilyl derivatives, and by 500-MHz1H-NMR spectroscopy. In addition, molar response factors for GLC analysis and extinction coefficients in the orcinol/Fe3+/HCl assay were determined.
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TL;DR: The I- type lectins are a subset of the immunoglobulin superfamily that are capable of carbohydrate-protein interactions and there are I-type lectins recognizing sialic acids, other sugars and glycosaminoglycans.
Abstract: The two members of the P-type lectin family, the cation-dependent mannose 6-phosphate receptor (CD-MPR) and the insulin-like growth factor II/mannose 6-phosphate receptor (IGF-II/MPR), are distinguished from all other lectins by their ability to recognize phosphorylated mannose residues. The P-type lectins play an essential role in the generation of functional lysosomes within the cells of higher eukaryotes by directing newly synthesized lysosomal enzymes bearing the mannose 6-phosphate (M6P) signal to lysosomes. At the cell surface, the IGF-II/MPR also binds to the nonglycosylated polypeptide hormone, IGF-II, targeting this potent mitogenic factor for degradation in lysosomes. Moreover, in recent years, the multifunctional nature of the IGF-II/MPR has become increasingly apparent, as the list of extracellular ligands recognized by this receptor has grown to include a diverse spectrum of M6P-containing proteins as well as nonglycosylated ligands, implicating a role for the IGF-II/MPR in a number of important physiological pathways. Recent investigations have provided valuable insights into the molecular basis of ligand recognition by the MPRs as well as the complex intracellular trafficking pathways traversed by these receptors. This review provides a current view on the structures, functions, and medical relevance of the P-type lectins.
238 citations
212 citations
TL;DR: The results suggest that this method of conjugation to a carrier protein may be a useful strategy to improve the immunogenicity of the type III group B Streptococcus polysaccharide in human subjects.
Abstract: The native capsular polysaccharide of type III group B Streptococcus elicits a specific antibody response in only 60% of nonimmune human subjects. To enhance the immunogenicity of this polysaccharide, we coupled the type III polysaccharide to tetanus toxoid. Prior to coupling, aldehyde groups were introduced on the polysaccharide by controlled periodate oxidation, resulting in the conversion of 25% of the sialic acid residues of the polysaccharide to residues of the 8-carbon analogue of sialic acid, 5-acetamido-3,5-dideoxy-D-galactosyloctulosonic acid. Tetanus toxoid was conjugated to the polysaccharide by reductive amination, via the free aldehyde groups present on the partially oxidized sialic acid residues. Rabbits vaccinated with the conjugate vaccine produced IgG antibodies that reacted with the native type III group B streptococcal polysaccharide (3/3 rabbits), while rabbits immunized with the unconjugated type III polysaccharide failed to respond (0/3 rabbits). Sera from animals receiving conjugate vaccine opsonized type III group B streptococci for phagocytic killing by human peripheral blood leukocytes, and protected mice against lethal challenge with live type III group B streptococci. The results suggest that this method of conjugation to a carrier protein may be a useful strategy to improve the immunogenicity of the type III group B Streptococcus polysaccharide in human subjects.
209 citations
TL;DR: Sialidases (neuraminidases), which liberate sialic acids from cellular compounds, had been known from very early on from studies with influenza viruses, and are studied because of their significance in development and, for instance, in cancer.
Abstract: Sialic acids are cytoprotectors, mainly localized on the surface of cell membranes with multiple and outstanding cell biological functions. The history of their structural analysis, occurrence, and functions is fascinating and described in this review. Reports from different researchers on apparently similar substances from a variety of biological materials led to the identification of a 9-carbon monosaccharide, which in 1957 was designated "sialic acid." The most frequently occurring member of the sialic acid family is N-acetylneuraminic acid, followed by N-glycolylneuraminic acid and O-acetylated derivatives, and up to now over about 80 neuraminic acid derivatives have been described. They appeared first in the animal kingdom, ranging from echinoderms up to higher animals, in many microorganisms, and are also expressed in insects, but are absent in higher plants. Sialic acids are masks and ligands and play as such dual roles in biology. Their involvement in immunology and tumor biology, as well as in hereditary diseases, cannot be underestimated. N-Glycolylneuraminic acid is very special, as this sugar cannot be expressed by humans, but is a xenoantigen with pathogenetic potential. Sialidases (neuraminidases), which liberate sialic acids from cellular compounds, had been known from very early on from studies with influenza viruses. Sialyltransferases, which are responsible for the sialylation of glycans and elongation of polysialic acids, are studied because of their significance in development and, for instance, in cancer. As more information about the functions in health and disease is acquired, the use of sialic acids in the treatment of diseases is also envisaged.
184 citations
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TL;DR: The I- type lectins are a subset of the immunoglobulin superfamily that are capable of carbohydrate-protein interactions and there are I-type lectins recognizing sialic acids, other sugars and glycosaminoglycans.
Abstract: The immunoglobulin superfamily is a large category of proteins defined by their structural similarity to immunoglobulins. The majority of these proteins are involved in protein-protein binding as receptors, antibodies or cell adhesion molecules. The I-type lectins are a subset of the immunoglobulin superfamily that are capable of carbohydrate-protein interactions. There are I-type lectins recognizing sialic acids, other sugars and glycosaminoglycans. The occurrence, structure, binding properties and (potential) biological functions of the I-type lectins are reviewed here.
174 citations
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TL;DR: This chapter discusses the different aspects of thiobarbituric acid assay of sialic acid, which is suitable for measuring the release of bound sialoic acid by sialidase and hydrolysis of sIALic acid-containing material must be carried out for the measurement of total sialsic acids.
Abstract: Publisher Summary This chapter discusses the different aspects of thiobarbituric acid assay of sialic acid. Periodate oxidation of the neuraminic acid backbone of sialic acids results in the formation of β -formylpyruvic acid from carbon atoms 1 to 4. The N -acetyl or N -glycolyl group of sialic acids apparently does not interfere with periodate oxidation. β -Formylpyruvic acid is coupled with 2-thiobarbituric acid to form a red chromophore with a maximum absorption at 549 mμ. It is found that as only free sialic acids are reactive in the assay, hydrolysis of sialic acid-containing material must be carried out for the measurement of total sialic acids. The assay is suitable for measuring the release of bound sialic acid by sialidase. A series of 2-keto, 3-deoxy sugar acids, found in bacteria, also react in the thiobarbituric acid assay. These produce a chromogen with a peak at 549 mμ. They can be readily distinguished from sialic acids because they are not reactive in the orcinol or direct Ehrlich assays for sialic acids. The hydrolysis frees all the sialic acids from several mucoproteins that have been tested except for brain tissue where release of sialic acids takes place for several hours.
6,264 citations
TL;DR: This chapter presents literature data on the high-resolution, 1H-NMR spectroscopy of carbohydrates derived from glycoconjugates and discusses the results for carbohydrates related to the glycoproteins of N-glycosylic type.
Abstract: Publisher Summary This chapter discusses the application of high-resolution, 1H-nuclear magnetic resonance (NMR) spectroscopy to the structural analysis of carbohydrates related to glycoproteins. Glycoproteins are biopolymers consisting of a polypeptide backbone bearing one or more covalently linked carbohydrate chains. The carbohydrate chains of glycoproteins may be classified according to the type of linkage to the polypeptide backbone. N-Glycosylic chains are attached to the amide group of asparagine (Asn), whereas the O-glycosylic chains are linked to the hydroxyl group of amino acid residues such as serine (Ser), threonine (Thr), and hydroxylysine (Hyl). The high-resolution, 1H-NMR spectroscopy technique, in conjunction with methylation analysis, is extremely suitable for the structural studies of N-, as well as on O-, glycosylic glycans. For the interpretation of the 1H-NMR spectrum of a carbohydrate chain in terms of primary structural assignments, the concept of “structural reporter groups” was developed. This means that the chemical shifts of protons resonating at clearly distinguishable positions in the spectrum, together with their coupling constants and the line widths of their signals, bear the information essential to permit the assigning of the primary structure. This chapter presents literature data on the high-resolution, 1H-NMR spectroscopy of carbohydrates derived from glycoconjugates. It also discusses the results for carbohydrates related to the glycoproteins of N-glycosylic type.
797 citations
TL;DR: This simple method of specifically introducing a radioactive label into cell surface sialic acids is useful in the study of cell surfaceSialic acid-containing glycoproteins.
Abstract: Low concentrations of sodium metaperiodate induce specific oxidative cleavage of sialic acids between carbon 7 and carbon 8 or carbon 8 and carbon 9. The aldehydes formed can easily be reduced with NaB3H4 to tritiated 5-acetamido-3,5-dideoxy-L-arabino-2-heptulosonic acid or 5-acetamido-3,5-dideoxy-L-arabino-2-octulosonic acid. At 0 degrees, the periodate anion penetrates the cell plasma membrane very slowly and only externally exposed sialic acids are oxidized. This was shown by (a) limited labeling of the sialoglycoproteins in a preparation of inside-out erythrocyte vesicles; (b) trapping 14C-labeled fetuin within resealed erythrocyte ghosts; fetuin was then poorly labeled, whereas the erythrocyte sialoglycoproteins were highly labeled; (c) comparison of labeled glycoproteins of mouse lymphoid cells before and after treatment with neuraminidase. This simple method of specifically introducing a radioactive label into cell surface sialic acids is useful in the study of cell surface sialic acid-containing glycoproteins.
482 citations
230 citations
01 Jan 1982
TL;DR: The discovery and the widespread occurrence of the sialic acids in mammalian tissues has been correlated with a range of different biological functions (see chapter J), and the known spectrum of derivatives covered in this chapter continues to expand.
Abstract: The discovery and the widespread occurrence of the sialic acids in mammalian tissues (Blix 1936, Klenk 1941) has been correlated with a range of different biological functions (see chapter J) which continues to expand. Although the literature on sialic acid occurrence is large (Gottschalk 1960, Blix and Jeanloz 1969, Tuppy and Gottschalk 1972, Schauer 1973, Ng and Dain 1976), it has been essentially limited to the vertebrates and some examples from the Echinodermata and Bacteria. Only one survey of sialic acid distribution in different phyla has been published (Warren 1963). Current data on sialic acid structure is compiled in Table 1, introducing the known spectrum of derivatives covered in this chapter.
168 citations