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1.
Günter Harms Gerd Reuter Anthony P. Corfield Roland Schauer 《Glycoconjugate journal》1996,13(4):621-630
The specificity of influenza C-virus binding to sialoglycoconjugates was tested with various naturallyO-acetylated gangliosides or syntheticallyO-acetylated sialic acid thioketosides, which revealed binding to 9-O-acetylatedN-acetylneuraminic acid. Binding was also observed with a sample of Neu5,7Ac2-GD3, however at a lower degree. Sialic acids with two or threeO-acetyl groups in the side chain of synthetic sialic acid derivatives are not recognized by the virus. In these experiments, bound viruses were detected with esterase substrates. Influenza C-virus was also used for the histological identification of mono-O-acetylated sialic acids in combination with an immunological visualization of the virus bound to thin-sections. The occurrence of these sialic acids was demonstrated in bovine submandibular gland, rat liver, human normal adult and fetal colon and diseased colon, as well as in human sweat gland. Submandibular gland and colon also contain significant amounts of glycoconjugates with two or three acetyl esters in the sialic acid side chain, demonstrating the value of the virus in discriminating between mono- and higherO-acetylation at the same site. The patterns of staining showed differences between healthy persons and patients with colon carcinoma, ulcerative colitis or Crohn's disease. Remarkably, some human colon samples did not showO-acetyl sialic acid-specific staining. The histochemical observations were controlled by chemical analysis of tissue sialic acids.Abbreviations BSA
bovine serum albumin
- BSM
bovine submandibular gland mucin
- HAU
haemagglutination units
- HPLC
high-performance liquid chromatography
- HPTLC
high-performance thin-layer chromatography
- Neu5Ac
N-acetylneuraminic acid
- Neu5,9Ac2
N-acetyl-9-O-acetylneuraminic acid
- Neu5,7,9Ac3
N-acetyl-7,9-di-O-acetylneuraminic acid
- Neu5,7,8,9Ac4
N-acetyl-7,8,9-tri-O-acetylneuraminic acid
- PBS
phosphate-buffered saline
- TLC
thin-layer chromatography
Dedicated to Prof. Dr Nathan Sharon on the occasion of his 70th birthday. 相似文献
2.
Roland Schauer G. Vinayaga Srinivasan Bernadette Coddeville Jean-Pierre Zanetta Yann Gurardel 《Carbohydrate research》2009,344(12):1494-4774
The sialic acids of the platypus, birds, and reptiles were investigated with regard to the occurrence of N-glycolylneuraminic (Neu5Gc) acid. They were released from tissues, eggs, or salivary mucin samples by acid hydrolysis, and purified and analyzed by thin-layer chromatography, high-performance liquid chromatography, and mass spectrometry. In muscle and liver of the platypus only N-acetylneuraminic (Neu5Ac) acid was found. The nine bird species studied also did not express N-glycolylneuraminic acid with the exception of an egg, but not tissues, from the budgerigar and traces in poultry. Among nine reptiles, including one turtle, N-glycolylneuraminic acid was only found in the egg and an adult basilisk, but not in a freshly hatched animal. BLAST analysis of the genomes of the platypus, the chicken, and zebra finch against the CMP-N-acetylneuraminic acid hydroxylase did not reveal the existence of a similar protein structure. Apparently monotremes (platypus) and sauropsids (birds and reptiles) cannot synthesize Neu5Gc. The few animals where Neu5Gc was found, especially in eggs, may have acquired this from the diet or by an alternative pathway. Since Neu5Gc is antigenic to man, the observation that this monosaccharide does not or at least only rarely occur in birds and reptiles, may be of nutritional and clinical significance. 相似文献
3.
Panayotis A. Siskos Maria-Helen E. Spyridaki 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,724(2):346
A simple, rapid and sensitive reversed-phase ion-pair high-performance liquid chromatographic method for the determination of N-acetylneuraminic acid and 2-deoxy-2,3-dehydro-N-acetylneuraminic acid in biological fluids is described. Determination of N-acetylneuraminic acid released by acidic hydrolysis, in serum, urine and saliva, and 2-deoxy-2,3-dehydro-N-acetylneuraminic acid in urine, without hydrolysis, was accomplished by injecting the sample without derivatization, into the chromatograph. Measurements were carried out isocratically within 6 min using a C18 column and a mobile phase of aqueous solution of triisopropanolamine, as ion-pair reagent, 60 mM, pH 3.5 at room temperature with UV absorbance detection. The present method is reported for the first time for the determination of sialic acids in biological fluids. Recoveries in serum, urine and saliva ranged from 90 to 102% and the limits of detection were 60 nM and 20 nM for the two sialic acids, respectively. The method has been applied to normal and pathological sera from patients with breast, stomach, colon, ovarian and cervix cancers, to normal urine and urine from patient with sialuria and to normal saliva. 相似文献
4.
Reinhard G. Kleineidam Olaf Hofmann Gerd Reuter Roland Schauer 《Glycoconjugate journal》1993,10(1):116-119
Fractionation of horse liver homogenate by centrifugation into heavy membranes at 10 000 × g, microsomal fraction at 105 000 × g, and the supernatant revealed sialate 9-O-lactoyltransferase activity only in the latter fraction. For the enzyme assay, the various fractions were incubated with14C labelled CMP-N-acetylneuraminic acid,N-acetylneuraminic acid and glycoconjugate-boundN-acetylneuraminic acid. Lactoylation was identified in three different TLC systems after acid hydrolysis and purification of the sialic acids in the incubation mixtures. Enzyme activity was found only in the supernatant fraction. Glycoconjugate-boundN-acetylneuraminic acid was the best substrate tested, although some lactoylation was also found when using CMP-N-acetylneuraminic acid. 相似文献
5.
The natural sialidase ofClostridium septicum was purified and characterized in parallel with the recombinant enzyme expressed byEscherichia coli. The two enzymes exhibit almost identical properties. The maximum hydrolytic activity was measured at 37 °C in 60mm sodium acetate buffer, pH 5.3. Glycoproteins like fetuin and saponified bovine submandibular gland mucin, most of them having (2-6) linked sialic acids, are preferred substrates, while sialic acids from gangliosides, sialyllactoses, or the (2-8) linked sialic acid polymer (colominic acid) are hydrolysed at lower rates. (2-3) Linkages are more rapidly hydrolysed than (2-6) bonds of sialyllactoses. The cleavage rate is markedly reduced by O-acetylation of the sialic acid moiety. These properties are similar to those of other secreted clostridial sialidases. The enzyme exists in mono-, di- and trimeric forms, the monomer exhibiting a molecular mass of 125 kDa, which is close to the protein mass of 111 kDa deduced from the nucleotide sequence of the cloned gene.Abbreviations BSM
bovine submandibular gland mucine
- CMM
cooked meat medium
- EDTA
ethylenediaminetetraacetic acid
- FPLC
fast performance liquid chromatography
- LB
Luria-Bertani
- MU-Neu5Ac
4-methylumbelliferyl--d-N-acetylneuraminic acid
- Neu5Ac
N-acetylneuraminic acid
- Neu5Ac2en
2-deoxy-2,3-didehydro-N-acetylneuraminic acid
- Neu4,5Ac2
N-acetyl-4-O-acetylneuraminic acid
- pI
isoelectric point
- SDS
sodium dodecyl sulfate 相似文献
6.
The sialic acid analogue,N-acetyl-4-deoxy-neuraminic acid, is readily activated by CMP-sialic acid synthase from bovine brain. We also show that sialyl-transfer from CMP-N-acetyl-4-deoxy-neuraminic acid to asialo-
1-acid glycoprotein is achieved at a high rate using Gal1-4GlcNAc (2.6)-sialyltransferase from rat liver.In contrast toVibrio cholerae sialidase, fowl plague virus sialidase liberates boundN-acetyl-4-deoxy-neuraminic acid from the glycoprotein. Thus, as opposed to the general view, the action of neither synthase nor transferase depends on the presence of the hydroxy group at C-4 ofN-acetylneuraminic acid.Abbrevations BSA
bovine serum albumin
- DTE
dithioerythritol
- HPLC
high performance liquid chromatography
- NeuAc
N-acetyl-d-neuraminic acid
- 4-deoxy-NeuAc
N-acetyl-4-deoxy-d-neuraminic acid
- 4-epi-NeuAc
4-acetamido-3,5-dideoxy-d-glycero-d-talononulosonic acid
- CMP-NeuAc
Cytidine-5-monophospho-N-acetylneuraminic acid
- CMP-4-deoxy-NeuAc
Cytidine-5-monophospho-N-acetyl-4-deoxy-neuraminic acid
- FPV-sialidase
Fowl plague virus sialidase
- VCN
Vibrio cholerae neuraminidase 相似文献
7.
Sialate-O-acetylesterase was purified almost 900-fold from particle-free supernatants of horse liver by gel filtration, ion-exchange
chromatography and isoelectric focussing. The native enzyme on gel filtration exhibits a molecular weight of 54,000 Da. It
was separated by isoelectric focussing into two forms with pI values of 4.8 and 5.7, respectively. The esterase with a lower pI hydrolyses only 9-O-acetyl groups from sialic acids (KM 1.1 mM), while that with the higher pI esterifies both 4- and 9-O-acetylated monosaccharides at similar rates (KM 0.3 M and 1.3 mM, respectively). Both forms are inactive with 7-O-acetylated N-acetylneuraminic acid. Enzyme assays were carried out at the pH optimum (pH 8.4–8.6) using free O-acetylated sialic acids followed by direct analysis of the reaction products by isocratic anion-exchange HPLC. Glycosidically
bound sialic acids can also be de-O-acetylated. Horse liver esterase seems to be an essential enzyme for the catabolism of 4-O-acetylated sialoglycoconjugates, since sialidase from this tissue cannot act on 4-O-acetylated sialic acids. 相似文献
8.
Ashok K. Shukla Norbert Scholz Ernst H. Reimerdes Roland Schauer 《Analytical biochemistry》1982,123(1):78-82
A rapid, isocratic high-performance liquid chromatographic method for the analysis of N-acetylneuraminic acid, N-glycolylneuraminic acid, and their O-acetylated derivatives is described. Separation of sialic acids and of other monosaccharides as sugar-borate complexes is achieved on an anion-exchange resin. The sialic acids elute as individual peaks after the other sugars tested. The method allows quantitative determination, for example, of amounts of N-acetylneuraminic acid as small as 10 nmol. On cation-exchange resin sialic acids cannot be differentiated, but can be separated from neutral and amino sugars, allowing the determination of as little as 3 nmol of total sialic acids. 相似文献
9.
Johannis P. Kamerling Josef Makovitzky Roland Schauer Johannes F.G. Vliegenthart Margret Wember 《Biochimica et Biophysica Acta (BBA)/General Subjects》1982,714(2):351-355
Analysis of the sialic acids obtained by mild acid hydrolysis of B lymphocytes reveals the presence of N-acetylneuraminic acid and 9-O-acetyl-N-acetylneuraminic acid. For T lymphocytes only N-acetylneuraminic acid has been demonstrated to occur. The applied methods include quantitative colorimetry, thin-layer chromatography and combined gas-liquid chromatography-mass spectrometry. 相似文献
10.
Roland Schauer Sabine Stoll Erich Zbiral Erwin Schreiner HanNelore H Brandstetter Andrea Vasella Franz Baumberger 《Glycoconjugate journal》1987,4(4):361-369
Various deoxy- and epi-derivatives ofN-acetylneuraminic acid were synthesized and tested for their substrate properties withN-acetylneuraminate lyase fromClostridium perfringens.N-Acetyl-9-deoxyneuraminic acid is a good substrate,N-acetylneuraminic acid derivatives with epimeric configuration at C-7, C-8 or both are cleaved slowly, whileN-acetyl-4-epi-,N-acetyl-4-deoxy-,N-acetyl-7-deoxy-andN-acetyl-8-deoxyneuraminic acid are resistant to enzyme action.N-Acetyl-4-deoxyneuraminic acid andN-acetyl-4-epineuraminic acid competitively inhibit the enzyme. These studies give further insight into a mechanism proposed for the reversible cleavage of sialic acids byN-acetylneuraminate lyase. 相似文献
11.
KDN is an abbreviation for 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid, and its natural occurrence was revealed in 1986 by a research group including the present authors. Since sialic
acid was used as a synonym for N-acylneuraminic acid at that time, there was an argument if this deaminated neuraminic acid belongs to the family of sialic
acids. In this review, we describe the 20 years history of studies on KDN (KDNology), through which KDN has established its
position as a distinct member of the sialic acid family. These studies have clarified that: (1) KDN occurs widely among vertebrates
and bacteria similar to the occurrence of the more common sialic acid, N-acetylneuraminic acid (Neu5Ac), but its abundant occurrence in animals is limited to lower vertebrates. (2) KDN is found
in almost all types of glycoconjugates, including glycolipids, glycoproteins and capsular polysaccharides. (3) KDN residues
are linked to almost all glycan structures in place of Neu5Ac. All linkage types known for Neu5Ac; α2,3-, α2,4-, α2,6-, and
α2,8- are also found for KDN. (4) KDN is biosynthesized de novo using mannose as a precursor sugar, which is activated to CMP-KDN and transferred to acceptor sugar residues. These reactions
are catalyzed by enzymes, some of which preferably recognize KDN, but many others prefer Neu5Ac to KDN. In addition to these
basic findings, elevated expression of KDN was found in fetal human red blood cells compared with adult red blood cells, and
ovarian tumor tissues compared with normal controls. KDNase, an enzyme which specifically cleaves KDN-linkages, was discovered
in a bacterium and monoclonal antibodies that specifically recognize KDN residues in KDNα2,3-Gal- and KDNα2,8-KDN-linkages
have been developed. These have been used for identification of KDN-containing molecules. Based on past basic studies and
variety of findings, future perspective of KDNology is presented. 相似文献
12.
Sialic acids as receptor determinants for coronaviruses 总被引:3,自引:0,他引:3
Among coronaviruses, several members are able to interact with sialic acids. For bovine coronavirus (BCoV) and related viruses,
binding to cell surface components containing
N-acetyl-9-
O-acetylneuraminic acid is essential for initiation of an infection. These viruses resemble influenza C viruses because they
share not only the receptor determinant, but also the presence of an acetylesterase that releases the 9-
O-acetyl group from sialic acid and thus abolishes the ability of the respective sialoglycoconjugate to function as a receptor
for BCoV. As in the case of influenza viruses, the receptor-destroying enzyme of BCoV is believed to facilitate the spread
of virus infection by removing receptor determinants from the surface of infected cells and by preventing the formation of
virus aggregates. Another coronavirus, porcine transmissible gastroenteritis virus (TGEV) preferentially recognizes
N-glycolylneuraminic acid. TGEV does not contain a receptor-destroying enzyme and does not depend on the sialic acid binding
activity for infection of cultured cells. However, binding to sialic acids is required for the enteropathogenicity of TGEV.
Interaction with sialoglycoconjugates may help the virus to pass through the sialic acid-rich mucus layer that covers the
viral target cells in the epithelium of the small intestine. We discuss that the BCoV group of viruses may have evolved from
a TGEV-like ancestor by acquiring an acetylesterase gene through heterologous recombination. 相似文献
13.
The dominant glycosylation mutants of MDAY-D2 mouse lymphoma cells, designated class 2 (D33W25 and D34W25) were selected for their resistance to the toxic effects of wheat germ agglutinin (WGA) and shown to express elevated levels of Neu5Gc. In accordance with this, the activity of CMP-Neu5Ac hydroxylase was found to be substantially higher in the mutant cells. The hydroxylase in the D33W25 mutant cells exhibited kinetic properties identical to those of the same enzyme from mouse liver. Growth rate experimentsin vivo andin vitro, where the mutant cells grew more slowly at low cell densities in serum-free medium and also formed slower growing tumours in syngeneic mice, indicate that CMP-Neu5Ac hydroxylase expression may be associated with altered growth of the mutant cells.Abbreviations WGA
wheat germ agglutinin
- Neu5Ac
N-acetyl--d-neuraminic acid
- Neu5Gc
N-glycology--d-neuraminic acid
- CMP-Neu5Ac
cytidine-5-monophospho-N-acetylneuraminic acid
- CMP-Neu5Gc
cytidine-5-monophospho-N-glycoloylneuraminic acid
- FACS
fluorescence-activated cell sorting
- buffer A
triethylamine hydrogen carbonate, pH 7.6 (concentration given at appropriate points in the text)
- SFM
serum free medium
- IMDM
Iscove's modified Dulbecco's medium
- CMP-Neu5Ac hydroxylase
CMP-N-acetylneuraminate: NAD(P)H oxido-reductase (N-acetyl hydroxylating) (EC 1.14.99.18); CMP-sialate hydrolase (EC 3.1.4.40); sialic acid-pyruvate lyase (EC 4.1.3.3) 相似文献
14.
Malykh YN Krisch B Gerardy-Schahn R Lapina EB Shaw L Schauer R 《Glycoconjugate journal》1999,16(11):731-739
Sialic acid-containing glycoconjugates are generally considered to be unique to the deuterostomes, a lineage of the animal kingdom which includes animals from the echinoderms up to the vertebrates. There are, however, two isolated reports of sialic acid occurring in the insect species Drosophila melanogaster and Galleria mellonella. Since insects are classified as protostomes, these findings call previous assumption on the phylogenetic distribution and thus on the evolution of sialic acids into question. Here, we report the occurrence of N-acetylneuraminic acid (Neu5Ac) in larvae of the cicada Philaenus spumarius. Cytochemical analysis of larval sections with lectins from Sambucus nigra and Limax flavus suggested the presence of sialic acids in the concrement vacuoles of the Malpighian tubules. The monoclonal antibody MAb 735, which is specific for polysialic acid, labelled the same structures. A chemical analysis performed by HPLC of fluorescent derivatives of sialic acids and by GLC-MS provided sound evidence for the presence of Neu5Ac in the Philaenus spumarius larvae. These data suggest that in this cicada Neu5Ac occurs in 2,8-linked polysialic acid structures and in 2,6-linkages. The results provide further evidence for the existence of sialic acids in insects and in linkages known to occur in glycoconjugates of deuterostomate origin. 相似文献
15.
T. J. Budd C. D. Dolman A. M. Lawson W. Chai J. Saxton F. W. Hemming 《Glycoconjugate journal》1992,9(5):274-278
N-Acetylneuraminic acid (Neu5Ac) andN-glycoloylneuraminic acid (Neu5Gc) are distributed widely in nature. Using a Carbopac PA-1 anion exchange column, we have determined the ratios of Neu5Ac and Neu5Gc in hydrolysates of platelets and their precursors: a rat promegakaryoblastic (RPM) cell line and a human megakaryoblastic leukemia cell line (MEG-01). The ratio of Neu5Gc:Neu5Ac in cultured RPM cells is 16:1, whereas in platelet rich plasma and cultured MEG-01 cells it is 1:38 and 1:28, respectively. The nature of these sialic acids from RPM cells was verified using thin layer chromatography and liquid secondary ion mass spectrometry. The relevance of increased Neu5Gc levels in early stages of development is discussed.Abbreviations Neu5Ac
N-acetylneuraminic acid
- Neu5Gc
N-glycoloylneuraminic acid
- RPM
rat promegakaryoblast
- MEG-01
human megakaryoblastic leukaemia cell line
- PAD
pulsed amperometric detection
- WGA
wheat germ agglutinin
- FCS
foetal calf serum
- PPEADF
phosphatidylethanolamine dipalmitoyl
- LSIMS
liquid secondary ion mass spectrometry
- HPAEC
high performance anion exchange chromatography
- TBA
thiobarbituric acid 相似文献
16.
Junya Mitoma Tatsuo Miyazaki Mark Sutton-Smith Misa Suzuki Hideo Saito Jiunn-Chern Yeh Takehiro Kawano Ole Hindsgaul Peter H. Seeberger Maria Panico Stuart M. Haslam Howard R. Morris Richard D. Cummings Anne Dell Minoru Fukuda 《Glycoconjugate journal》2009,26(5):511-523
E-, P- and L-selectins critically function in lymphocyte recirculation and recruiting leukocytes to inflammatory sites. MECA-79
antibody inhibits L-selectin-mediated lymphocyte adhesion in several species and does not require sialic acid in its epitope.
Many other antibodies, however, recognize human selectin ligands expressing N-acetylneuraminic acid but not mouse selectin ligands expressing N-glycolylneuraminic acid, suggesting that difference in sialic acid in sialyl Lewis X leads to differential reactivity. We
found that HECA-452 and FH6 monoclonal antibodies bind Chinese hamster ovary (CHO) cells expressing N-acetylneuraminyl Lewis X oligosaccharide but not its N-glycolyl form. Moreover, synthetic N-acetylneuraminyl Lewis X oligosaccharide but not its N-glycolyl oligosaccharide inhibited HECA-452 and FH6 binding. By contrast, E-, P- and L-selectin bound to CHO cells regardless
of whether they express N-acetyl or N-glycolyl form of sialyl Lewis X, showing that selectins have a broader recognition capacity than HECA-452 and FH-6 anti-sialyl
Lewis x antibodies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Gerd Reuter Reinhard Pfeil Johannis P. Kamerling Johannes F.G. Vliegenthart Roland Schauer 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,630(2):306-310
The novel sialic acid 4-O-acetyl-9-O-lactyl-N-acetylneuraminic acid has been identified as a constituent of horse submandibular gland glycoproteins in addition to the already know equine sialic acids, N-acetylneuraminic acid, 4-O-acetyl-N-acetylneuraminic acid, 9-O-acetyl-N-acetylneuraminic acid, 4,9-di-O-acetyl-N-acetylneuraminic acid, N-glycolylneuraminic acid, 4-O-acetyl-N-glycolylneuraminic acidand 9-O-acetyl-N-glycolylneuraminic acid. The structure has been established by combined gas-liquid chromatography-mass spectrometry. 相似文献
18.
Anthony P. Corfield Clarice Do Amaral Corfield Rüdiger W. Veh Susan A. Wagner John R. Clamp Roland Schauer 《Glycoconjugate journal》1991,8(4):330-339
Two mucins were isolated from bovine submandibular glands and termed major and minor on a quantitative basis. The major mucin representing over 80% of the total glycoprotein fraction contained 37% of its dry weight as protein in contrast to 62% for the minor mucin. Differences in the amino acid composition reflected the higher proportion of typically non-glycosylated peptide in the minor mucin. The molar ratio ofN-acetylgalactosamine to serine plus threonine was 0.82 in major and 0.65 in minor mucins, indicating a lower degree of substitution of potential glycosylation sites in the minor mucin.Differences in the carbohydrate composition were found largely related to the sialic acids, with higher relative amounts ofN-glycoloylneuraminic acid in the minor mucin. In addition, the proportion of di-O-acetylated sialic acids was higher in the major mucin. The rate of sialidase action on the two mucins could be correlated with the content ofN-glycoloylneuraminic acid in each glycoprotein. There was no difference in the type of oligosaccharide found in each mucin and the differences in relative proportions reflected the monosaccharide composition for the two mucins. Gel filtration on Sepharose CL 2B showed a lower molecular weight distribution for the minor in contrast to the major mucin which was partially excluded. Density gradient centrifugation reflected this variation. SDS-PAGE demonstrated a regular banding pattern for the major mucin with a lowest subunit size of 1.8×105 Da and aggregates in excess of 106 Da, while the minor mucin ranged from 3.0 × 105 to 106 Da. The chemical composition of the isolated mucins was compared with previous histochemical analysis of mucin distribution in bovine submandibular glands and indicates a possible cellular location for each mucin.Abbreviations PBS
0.01m sodium phosphate buffer, pH 7.3, containing 0.15m NaCl
- Neu5Ac
N-acetylneuraminic acid
- Neu5Gc
N-glycoloylneuraminic acid
- GalNAc-ol
N-acetylgalactosaminitol 相似文献
19.
Daniel Gagiannis Reinhart Gossrau Werner Reutter Martin Zimmermann-Kordmann Rüdiger Horstkorte 《Biochimica et Biophysica Acta (BBA)/General Subjects》2007
Sialic acids play an important role during development, regeneration and pathogenesis. The precursor of most physiological sialic acids, such as N-acetylneuraminic acid is N-acetyl-d-mannosamine. Application of the novel N-propanoylmannosamine leads to the incorporation of the new sialic acid N-propanoylneuraminic acid into cell surface glycoconjugates. Here we analyzed the modified sialylation of several organs with N-propanoylneuraminic acid in mice. By using peracetylated N-propanoylmannosamine, we were able to replace in vivo between 1% (brain) and 68% (heart) of physiological sialic acids by N-propanoylneuraminic acid. The possibility to modify cell surfaces with engineered sialic acids in vivo offers the opportunity to target therapeutic agents to sites of high sialic acid concentration in a variety of tumors. Furthermore, we demonstrated that application of N-propanoylmannosamine leads to a decrease in the polysialylation of the neural cell adhesion molecule in vivo, which is a marker of poor prognosis for some tumors with high metastatic potential. 相似文献
20.
Corfield AP Donapaty SR Carrington SD Hicks SJ Schauer R Kohla G 《Glycoconjugate journal》2005,22(7-9):409-416
O-Acetylated sialic acids have been reported in many sialoglycoproteins where they mediate a variety of immune and other biological
events. We have previously demonstrated that the protective mucus barrier on the surface of the canine eye contains sialoglycoproteins.
We have also investigated the occurrence of O-Acetylated sialic acids in these ocular mucins. Mucus aspirated from the surface of normal dog eyes and those with keratoconjunctivitis
sicca (KCS) was fractionated into three pools by density gradient centrifugation. Sialic acids comprised 0.6–0.9% of the dry
weight of the mucins isolated. The sialic acid profile in these pools was examined using HPLC. O-Acetylated sialic acids, mainly Neu5,9Ac2, were detected in normal animals and made up 10–30% of the total sialic acids detected. A doubling of the sialic acid content
was found in KCS mucins, but the level of 9-O-Acetylated sialic acid was reduced below 4% of total.
Histological analysis of conjunctival tissue from normal and KCS dogs showed the presence of sialic acids, detected with the
α(2–6) sialic acid-specific lectin Sambucus nigra, in the goblet cells and corresponding to the staining pattern for MUC5AC, the major ocular-secreted mucin gene product.
In KCS animals a disruption of the normal pattern of conjunctival goblet cells was seen with preservation of the pattern of
lectin binding observed in normal animals.
Thus the data demonstrate the presence of mono-O-Acetylated sialic acids in normal canine ocular mucins and a loss of this population of sialic acids in dry eye disease in
spite of a significant increase in total sialic acids in KCS mucin. 相似文献