Chemistry, biochemistry and biology of sialic acids

Schauer, Roland; Kamerling, Johannis P.

doi:10.1016/s0167-7306(08)60624-9

Cited by 167 publications

(230 citation statements)

References 1,028 publications

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“…Cell membranes containing sialic acid contribute to the negative charge of the membrane (Rosenberg, 1995). Cell aggregation may be prevented by the repulsive effects of the negatively charged sialic acid, as was observed when studying the adhesion of culture cells to their substratum (Schauer & Kamerling, 1997). Cell adhesion may be facilitated via positively charged substances or Ca 2 þ bridges which break the repulsive effect of sialic acids.…”

Section: Sialic Acid and Cognitionmentioning

confidence: 97%

“…It is now known that sialic acids comprise a family of 43 naturally occurring derivatives of the nine-carbon sugar neuraminic acid (5-amino-3,5-dideoxy-D-glycero-D-galactononulsonic acid) (Schauer et al, 1995;Schauer & Kamerling, 1997). One branch of the sialic acid family is N-acetylated to form N-acetylneuraminic acids (Neu5Ac, NANA, Sia), which are the most widespread form of sialic acid and almost the only form found in humans (Figure 1).…”

Section: Structure and State Of Sialic Acid In Naturementioning

confidence: 99%

“…The majority (65%) is present in gangliosides and glycoproteins (32%) with the remaining 3% as free sialic acid (Brunngraber et al, 1972). However, gangliosides are not uniformly distributed within the human body (Rosenberg, 1995;Schauer & Kamerling, 1997). Ganglioside concentration in brain grey matter is 15 times that of large visceral organs such as liver, lung, and spleen and 500 times greater than intestinal mucosa (Table 1).…”

Section: Figurementioning

confidence: 99%

“…Sialic acid always occupies the terminal position of milk oligosaccharides, and the bond may be cleaved even if the remainder of the chain resists digestion. Autohydrolysis has also been claimed because sialic acids are relatively strong acids (pKa 2.2-3.0) (Schauer & Kamerling, 1997). Rat intestinal cell walls are highly permeable to free sialic acid.…”

Section: Digestion and Absorption Of Sialic Acidmentioning

confidence: 99%

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The role and potential of sialic acid in human nutrition

2003

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Sialic acids are a family of nine-carbon acidic monosaccharides that occur naturally at the end of sugar chains attached to the surfaces of cells and soluble proteins. In the human body, the highest concentration of sialic acid (as N-acetylneuraminic acid) occurs in the brain where it participates as an integral part of ganglioside structure in synaptogenesis and neural transmission. Human milk also contains a high concentration of sialic acid attached to the terminal end of free oligosaccharides, but its metabolic fate and biological role are currently unknown. An important question is whether the sialic acid in human milk is a conditional nutrient and confers developmental advantages on breast-fed infants compared to those fed infant formula. In this review, we critically discuss the current state of knowledge of the biology and role of sialic acid in human milk and nervous tissue, and the link between sialic acid, breastfeeding and learning behaviour.

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Section: Sialic Acid and Cognitionmentioning

confidence: 97%

Section: Structure and State Of Sialic Acid In Naturementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Digestion and Absorption Of Sialic Acidmentioning

confidence: 99%

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The role and potential of sialic acid in human nutrition

2003

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“…The structure, occurrence and general functions of sialic acids have been extensively reviewed (20)(21)(22)(23)(24)(25). Some important functions attributed to sialic acids are : (1) sialic acids contribute significantly to the overall negative charge of cell surface and glycoproteins.…”

Section: What Sialic Acid Ismentioning

confidence: 99%

Sialic acid in cardiovascular diseases

Nigam

Narain

Kumar

2006

Indian J Clin Biochem

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Sialic acid, the acylated derivatives of 9-carbon sugar neuraminic acid, present as terminal component of oligosaccharide chains of many glycoproteins and glycolipids, has been recognized to be involved in the regulation of a great variety of biological phenomena. Studies have shown that serum sialic acid predicts both coronary heart disease and stroke mortality and reflects the existence or activity of an atherosclerotic process. Most of the studies have shown an elevation in serum sialic acid concentration in coronary heart disease and a positive correlation between the raised serum sialic acid and the severity of the coronary lesions is observed. However, a few contradictory reports are also available. Racial differences in serum sialic acid have also been reported and correlated with international differences in the prevalence of atherosclerosis. Reduced sialic acid content of platelets, erythrocytes and lipoproteins may play important role in the pathogenesis of atherosclerosis. Elucidation of the mechanism of alternation in sialic acid concentration may throw more light on its potential clinical utility. Hence more studies are needed to designate sialic acid as a cardiovascular risk factor / marker.

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Glycoprotein Analysis: General Methods

Debray¹,

Spik²

2000

Encyclopedia of Analytical Chemistry

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Glycosylation is a common co‐ and post‐translational modification of a protein which may have profound effects on protein structure and function. Many biologically interesting proteins are glycosylated at their asparagine, serine, and threonine residues. Glycosylation has now been recognized as being more ubiquitous and structurally varied than all other types of post‐translational modifications combined. The glycosylation pattern of a glycoprotein is not random but is dependent on cell type, physiological conditions and, in some cases, disease states. Carbohydrate chains or glycans attached to the peptide backbone are classified according to the nature of the linkage to the peptide and their structure; both of these parameters allow the definition of common cores. In addition to the extreme structural diversity and complexity of glycan structures, one feature of protein glycosylation is the presence at a single site of any one of a number of glycan structures. This property gives rise to an extremely heterogeneous population of glycoproteins, termed glycoforms. The complexity of the glycan structures, the multiple substitutions (microheterogeneity) at glycosylation sites, and the structural diversity associated with the protein backbone itself represent an enormous task for analytical structural studies. Indirect methods such as immunological approaches using antibodies or lectins provide some structural information concerning the nature of glycans. Prior to their structural study, glycans have to be released from the protein backbone by enzymatic or chemical methods. Different endoenzymes such as N ‐glycanase ® allow a complete deglycosylation of glycoproteins, providing a pool of oligosaccharides which may be further fractionated. Establishment of the site heterogeneity and assessment of the different glycoforms require isolation and analysis of the individual glycopeptides generated after hydrolysis with specific proteases. Fractionation of glycans or glycopeptides can be achieved by different high‐performance liquid chromatography (HPLC) or electrophoretic procedures. Lectins, due to their extreme specificities with regard to monosaccharide or oligosaccharide motifs, represent powerful tools for sequential glycan fractionation. Traditionally, a complete structural analysis of the glycan structures, including determination of the carbohydrate sequence and the sugar linkage, has been a tedious, multidisciplinary task. Characterization and determination of the relative amount of individual constituent monosaccharides is generally obtained by gas–liquid chromatography (GLC) after hydrolysis of the oligosaccharide chain. Information concerning the nature of linkages and branching points is furnished by the methylation procedure. Nevertheless, these chemical sequencing methods often necessitate milligrams of material. To progress from this situation, sensitive physicochemical or enzymatic methods have been developed. The nuclear magnetic resonance (NMR) study of oligosaccharides, even of the less sensitive of the physicochemical techniques, is extremely powerful because it allows determination in a mixture of glycans, the complete structure of individual glycans including nature of monosaccharides, sequence, type of linkages, anomericity and branching points. The recent advances in mass spectrometry (MS) techniques, mainly matrix‐assisted laser desorption/ionization (MALDI) or electrospray ionization (ESI), have provided very sensitive means for the analysis of oligosaccharides and glycopeptides. The gain in sensitivity associated with a minimum number of sample manipulation steps allows work at the submicrogram level. The use of enzyme reagents is rapidly becoming popular in modern carbohydrate analysis because of their inherent selectivities for a sugar substrate and its linkage type. Exoglycosidases can be used in conjunction with other methods such as MALDI/MS or fluorophore‐assisted carbohydrate electrophoresis (FACE) separation. Complete structural information is now feasible for low‐microgram and submicrogram quantities of a glycoprotein; this quality of performance places the field of carbohydrate analysis closer to the sequencing methods available for other biomolecules, proteins or nucleic acids.

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Chemistry, biochemistry and biology of sialic acids

Cited by 167 publications

References 1,028 publications

The role and potential of sialic acid in human nutrition

The role and potential of sialic acid in human nutrition

Sialic acid in cardiovascular diseases

Glycoprotein Analysis: General Methods

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