The Biological Role of Sialic Acid at the Surface of the Cell

Jeanloz, Roger W.; Codington, John F.

doi:10.1007/978-1-4684-2226-9_7

Cited by 60 publications

(22 citation statements)

References 175 publications

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“…Participation of membrane sialic acid in many biologic reactions has been described (45) and several reactions may relate to its role in modulation of the alternative pathway. Senescent human erythrocytes have diminished amounts of sialic acid residues (46), and sialidase-treated erythrocytes of several mammalian species are rapidly removed from the circulation by sequestration in the liver (27).…”

Section: Methodsmentioning

confidence: 99%

Regulation by membrane sialic acid of β1H-dependent decay-dissociation of amplification C3 convertase of the alternative complement pathway

Fearon

1978

Proc. Natl. Acad. Sci. U.S.A.

386

231

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Sheep erythrocytes in their native state did not activate the alternative complement pathway, as measured by Iysis in dilutions of normal human serum containing [ethyl-enebis(oxyethylenenitrilo)J tetraacetic acid but acquired this capacity after membrane sialic acid residues had been removed (by sialidase) or modified (by NaIO4). Activation of the alternative pathway by sheep erythrocytes required removal or modification of at least 40% of the membrane sialic acid to reach threshold, and it increased proportionately when larger amounts of sialic acid had been affected. Studies with isolated proteins of the alternative pathway demonstrated that the altered erythrocyte membranes resembled natural activators in protecting bound C3b from inactivation by C3b inactivator and j#1H and protecting bound amplification C3 convertase (C3bBb) from decay-dissociation by fl1H. A 1% decrease in intact sialic acid was associated with a 1% decrease in fl1H activity in decay-dissociation of membrane bound C3bBb. Because removal of the C8 and C9 carbon atoms from the polyhydroxylated side chain of sialic acid by oxidation with NaIQ4 was functionally equivalent to removal of the entire sialic acid moiety, secondary effects of the latter reaction, such as diminution of the negative charge of the membrane or exposure of penultimate galactose residues, were not considered to be responsible for the altered activity of j#1H. These studies suggest that facilitation, by membrane sialic acid residues, of the interaction between bound C3b and ,B1H is essential to prevent the particle from effectively activating the alternative pathway.Activation of the classical complement pathway is dependent on primary recognition of foreign substances by IgG or IgM (1, 2), whereas activation-of the alternative complement pathway is not necessarily dependent on antibody for formation of its C3 convertase. In the human, this latter pathway can serve a primary recognition function for various particulate microbial polysaccharides-such as zymosan (3), a derivative of yeast cell walls, and Gram-negative bacterial lipopolysaccharide (4)-and certain mammalian cells such as rabbit erythrocytes (5) and some human lymphoblastoid cell lines (6). Cleavage of C3, a fl-globulin of Mr 185,000, by the alternative pathway occurs in two distinct phases: (i) continuous low-grade fluid phase generation of C3b, the 180,000 Mr cleavage fragment of C3 by interaction of native C3, B, D, and properdin (7, 8) that is independent of an activating particle and (ii) subsequent C3b-dependent amplified cleavage of C3 by a particle-associated C3 convertase (9, 10). Significant C3b deposition occurs only in the latter phase in which C3b (11) reversibly binds B, a 90,000 Mr fl-globulin that is then cleaved by D (11, 12) (9), rabbit erythrocytes (10), and Escherichia coli (25) is relatively resistant to decay-dissociation by #1H. Similarly, C3b is rapidly inactivated by C3bINA in a proteolytic reaction that is accelerated by flH (24, 26); however, if C3b is bound to an activator,...

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Section: Methodsmentioning

confidence: 99%

Regulation by membrane sialic acid of β1H-dependent decay-dissociation of amplification C3 convertase of the alternative complement pathway

Fearon

1978

Proc. Natl. Acad. Sci. U.S.A.

386

231

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“…The occurrence and nature of various Nacylated and O-acylated neuraminic acids is now well documented [l -31, and the pattern distribution is characteristic for the animal species. Sialic acids are implicated in many cellular processes [4], and the high number of the 0-acylated derivatives points to the importance of understanding the biological role of these substances. In a preliminary approach, a precise evaluation of the behaviour of the main enzymes involved in the metabolism of sialic acids is…”

mentioning

confidence: 99%

Metabolism of 4‐O‐Methyl‐N‐acetylneuraminic Acid a Synthetic Sialic Acid

Beau

Schauer

1980

European Journal of Biochemistry

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1. 4-0-Methyl-N-acetylneuraminic acid shows a strong positive periodate-thiobarbiturate reaction. The mechanism of dye formation in this test for sialic acids is discussed in view of the studies already published.2. An efficient preparation of a tritium-labelled 4-0-methyl-N-acetylneuraminic acid, with high specific radioactivity, by an oxymercuration-demercuration procedure is presented.3. Sialyltransferase activities in microsomal fractions of equine liver using desialylated fetuin are studied. The enzyme activity, assayed in a radioactive procedure, shows an apparent K , value for CMP-N-acetylneuraminic acid of 0.7 mM, whereas this value is 3.4 mM for CMP-4-0-methyl-N-acetylneuraminic acid. Differences are also observed in the maximal velocity for the two substrates.4. The equine liver system can be used to prepare substantial amounts of fetuin containing radioactive N-acetylneuraminic acid or 4-0-methyl-N-acetylneuraminic acid. The isolated reaction products show similar sialic acid release by treatments with acid or fowl-plague virus neuraminidase. In contrast, 4-0-methyl-N-acetylneuraminic acid-fetuin displays a marked resistance to desialylation by Vibrio cholerae neuraminidase.5. Free 4-0-methyl-N-acetylneuraminic acid is completely resistant to the action of acylneuraminate pyruvate-lyase. It does not inhibit the enzymic cleavage reaction of N-acetylneuraminic acid.6. The influence of a substitution at C-4 of neuraminic acid on the enzymatic reaction mechanisms is discussed.The acylneuraminic acids (sialic acids), widely distributed in animal tissues, are important components of oligosaccharides, glycolipids and glycoproteins. The occurrence and nature of various Nacylated and O-acylated neuraminic acids is now well documented [l -31, and the pattern distribution is characteristic for the animal species. Sialic acids are implicated in many cellular processes [4], and the high number of the 0-acylated derivatives points to the importance of understanding the biological role of these substances. In a preliminary approach, a precise evaluation of the behaviour of the main enzymes involved in the metabolism of sialic acids is

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“…The glycocalyx is particularly rich in carbohydrate moieties, above all sialylglycoconjugates; and some authors have suggested that terminal sialic acid residues play a role in several functions, including protection of cells from dehydration, transport of metabolites and ions across the plasmalemma, and hormone-binding [24]. The decrease in WGA reaction after b-elimination or Endo-F digestion suggests that the GlcNAc residues labeled by this lectin belong to both N-and O-linked oligosaccharides.…”

Section: Discussionmentioning

confidence: 99%