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Horn Evan J - - 2008
Sialic acid, an important carbohydrate found incorporated on the cell surface of many organisms, has been modified for use in a wide range of biological and pharmaceutical applications. We hypothesized that 4,7,8,9-tetra-O-acetyl-2-deoxy-2,3-dehydro-N-acetyl neuraminic acid methyl ester (4) could be efficiently synthesized in a one-pot reaction by heating peracetylated sialic acid ...
Chao Chin-Sheng - - 2008
Inexpensive and readily available sulfonic acids, p-toluenesulfonic acid, and sulfuric acid are versatile and efficient catalysts for the peracetylation of a broad spectrum of carbohydrate substrates in good yield and in a practical time frame. Three appealing features in sulfonic acid-catalyzed acetylation of free sugars were explored including (1) suppression ...
Newstead Simon L - - 2008
Clostridium perfringens is a Gram-positive bacterium responsible for bacteremia, gas gangrene, and occasionally food poisoning. Its genome encodes three sialidases, nanH, nanI, and nanJ, that are involved in the removal of sialic acids from a variety of glycoconjugates and that play a role in bacterial nutrition and pathogenesis. Recent studies ...
Nabekura Tomohiro - - 2008
PURPOSE: For the development of a safe and effective dual inhibitor of anticancer drug efflux transporters P-glycoprotein and multidrug resistance protein 1 (MRP1) to conquer multidrug resistance, we investigated the effects of dietary phytochemicals on the functions of P-glycoprotein and MRP1. METHODS: The effects of dietary phytochemicals on the functions ...
Matsuno Kanae - - 2008
A simple and rapid fluorimetric method was developed for detection and quantitative analysis of sialic acids in glycoproteins. Sialic acid residues in glycoproteins were specifically oxidized with periodate at 0 degrees C for 45 min. Formaldehyde generated from carbon 9 (C-9) of sialic acid was converted specifically to fluorescent dihydropyridine ...
Saddic George N - - 2008
Oligosaccharides in glycoproteins by their very nature influence many aspects of protein function, e.g., half-life and activity/potency. Recombinant IgGs constitute a major portion of therapeutic proteins. Though the glycans in IgGs account for about 2% of the total weight, they influence biologic activity apart from antigen binding. Characterization of the ...
Pence Sadrettin - - 2008
Epilepsy, the most common neurological disorder worldwide, changing cellular interactions and connectivity may have effects on sialic acid levels. A total of 80 mice were separated into 8 groups: the sham, control, pentylentetrazole (PTZ), PTZ plus progesterone, five dose progesterone, single dose progesterone, kindling, and kindling plus progesterone groups. Brains ...
Nanetti L L Department of Neurological Science, Faculty of Medicine, Marche Polytechnic University, Italy. - - 2008
Stroke is a heterogeneous syndrome caused by multiple disease mechanisms, resulting in a disruption of cerebral blood flow with subsequent tissue damage. It is well known that erythrocytes have a large amount of sialic acid and could represent a model to investigate changes occurring in a pathology like stroke. The ...
Sagis Leonard M C - - 2008
We have synthesized a new amphiphilic block oligomer by the enzymatic linking of a fatty acid (lauric acid) to a fructan oligomer (inulin) and tested the functionality of this carbohydrate derivative in foam stabilization. The structure of the modified oligosaccharide was found to be (Fruc)n(Glc)1CO-C11H23, which implies that on average ...
Miyazaki Tatsuo T Tumor Microenvironment Program, Glycobiology Unit, Cancer Research Center, Burnham Institute for Medical Research, La Jolla, CA 92037, - - 2008
It is widely reported that derivatives of sugar moieties can be used to metabolically label cell surface carbohydrates or inhibit a particular glycosylation. However, few studies address the effect of substitution of the cytidylmonophosphate (CMP) portion on sialyltransferase activities. Here we first synthesized 2'-O-methyl CMP and 5-methyl CMP and then ...
Severi Emmanuele - - 2008
The acquisition of host-derived sialic acid is an important virulence factor for some bacterial pathogens, but in vivo this sugar acid is sequestered in sialoconjugates as the alpha-anomer. In solution, however, sialic acid is present mainly as the beta-anomer, formed by a slow spontaneous mutarotation. We studied the Escherichia coli ...
Johnson Daniel - - 2008
N-linked glycans, including sialic acids, are integral components of ion channel complexes. To determine if N-linked sugars can modulate a rapidly inactivating K+ channel, the glycosylated Drosophila melanogaster Shaker K+ channel (ShB) and the N-glycosylation-deficient mutant (ShNQ), were studied under conditions of full and reduced sialylation. Through an apparent electrostatic ...
Pence Sadrettin - - 2007
Epilepsy can be described as a group of neurological disorders, characterized by recurrent episodes of convulsive seizures, loss of consciousness, sensory disturbances, abnormal behavior, or all of these. Altered glutathione metabolism in association with increased oxidative stress has been implicated in the pathogenesis of many diseases such as seizures. It ...
Isaev Dmytro - - 2007
The extracellular membrane surface contains a substantial amount of negatively charged sialic acid residues. Some of the sialic acids are located close to the pore of voltage-gated channel, substantially influencing their gating properties. However, the role of sialylation of the extracellular membrane in modulation of neuronal and network activity remains ...
Díaz Alcira Ofelia - - 2008
This study addresses the histomorphology, the histochemistry and the distribution of glycoconjugates (GCs) in the mucosa of the digestive tract of the weakfish Cynoscion guatucupa. The histological characterization of the buccopharyngeal cavity and the esophagus revealed that they are lined by a stratified epithelium where the mucosa is thrown into ...
Johnston Jason W - - 2008
Nontypeable Haemophilus influenzae is an opportunistic human pathogen causing otitis media in children and chronic bronchitis and pneumonia in patients with chronic obstructive pulmonary disease. The outer membrane of nontypeable H. influenzae is dominated by lipooligosaccharides (LOS), many of which incorporate sialic acid as a terminal nonreducing sugar. Sialic acid ...
Blixt Ola - - 2008
Here we demonstrate that glycan microarrays can be used for high-throughput acceptor specificity screening of various recombinant sialyltransferases. Cytidine-5'-monophospho-N-acetylneuraminic acid (CMP-Neu5Ac) was biotinylated at position 9 of N-acetylneuraminic acid (Neu5Ac) by chemoenzymatic synthesis generating CMP-9Biot-Neu5Ac. The activated sugar nucleotide was used as donor substrate for various mammalian sialyltranferases which transferred ...
Johnston Jason W - - 2007
Virulence of nontypeable Haemophilus influenzae (NTHi) is dependent on the decoration of lipooligosaccharide with sialic acid. This sugar must be derived from the host, as NTHi cannot synthesize sialic acids. NTHi can also use sialic acid as a carbon source. The genes encoding the sialic acid transporter and the genes ...
Kim Hyoung Jin - - 2007
Cytotoxic T-lymphocyte antigen 4-immunoglobulin (CTLA4Ig) has immunosuppressive activity and the ability to induce immune tolerance. There has been no report of its glycosylation ratio or of the role of its glycans. We investigated the terminal sialylation of rice cell-derived recombinant human CTLA4Ig (rrhCTLA4Ig) using lectins. The glycosylation ratios of rrhCTLA4Ig ...
Severi Emmanuele E Department of Biology (Area 10), University of York, PO Box 373, York YO10 5YW, - - 2007
Sialic acid occupies the terminal position within glycan molecules on the surfaces of many vertebrate cells, where it functions in diverse cellular processes such as intercellular adhesion and cell signalling. Pathogenic bacteria have evolved to use this molecule beneficially in at least two different ways: they can coat themselves in ...
Gao Ganpan - - 2007
The synthesis of phenoxyphenyl, phenoxybenzyl, biphenyl, and phenyltriazole substituted sialic acid derivatives as mimics of the tri- and tetrasaccharide epitopes of GQ1balpha is described. These synthetically easily available sialosides show comparable or even enhanced affinity to MAG compared with the natural tri- and tetrasaccharide epitopes and form a new class ...
Galuska Sebastian P - - 2007
Oligo- and polysialic acids (oligo/polySia) are characterized by a high diversity in nature due to the different types of sialic acids linked to each other and glycosidic linkages involved. Considering the methods that are presently available for analysis of oligo/polySia chains, only fluorometric anion-exchange high-performance liquid chromatography (HPLC) analysis, fluorometric ...
Poornima B Lakshmanamurthy - - 2007
Glycodelin A (GdA), a dimeric lipocalin, expressed by the uterine endometrium, is an immunomodulatory agent and induces apoptosis in T-cells. In this study we demonstrate that two populations of GdA with subtle differences in their net ionic charge are present in the amniotic fluid and that, apoptotic activity is exhibited ...
Bork Kaya - - 2007
Sialylation (e.g. expression of sialic acid) plays a crucial role for function and stability of most glycoproteins. The key enzyme for the biosynthesis of sialic acid is the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine-kinase (GNE). Mutations in the binding site of the feedback inhibitor CMP-sialic acid of the GNE leads to sialuria, a disease ...
Jayant Sreeja - - 2007
PURPOSE: To evaluate a novel targeted anticancer prodrug consisting of several copies of sialic acid (SA, targeting moiety), doxorubicin (DOX), citric acid (multifunctional spacer) and poly(ethylene glycol) (PEG, carrier). METHODS: alpha, omega bis carboxyl PEG was covalently conjugated with multiple copies of SA and DOX through a citric acid spacer ...
Kisa Fumiaki - - 2007
Enantiomeric pairs of sialic acid, D- and L-NeuAc (N-acetylneuraminic acid), were converted to D- and L-arabinose, respectively, by chemical degradation. Using this method, the absolute configuration of the sialic acid residues, NeuAc and NeuGc (N-glycolylneuraminic acid), in the gangliosides from the sea cucumber Cucumaria echinata was determined to be the ...
Yu Hai H Department of Chemistry, University of California-Davis, One Shields Avenue, Davis, CA 95616, - - 2007
Sialyl Tn (STn) and sialyl lactoside derivatives containing O-acetylated sialic acid residues have been chemoenzymatically synthesized using a one-pot three-enzyme system and conjugated to biotinylated human serum albumin (HSA) using an adipic acid para-nitrophenyl ester coupling reagent. This approach provides an efficient and general protocol for preparing carbohydrate-protein conjugates containing ...
Reinke Stefan O - - 2007
The bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) is the key enzyme of the biosynthesis of sialic acids, terminal components of glycoconjugates associated with a variety of cellular processes. Two novel isoforms of human GNE, namely GNE2 and GNE3, which possess extended and deleted N-termini, respectively, were characterized. GNE2 was also ...
Chrostek Lech - - 2007
AIMS: Total sialic acid (TSA) has been suggested as a marker for chronic alcohol abuse. It seems that the elevation of TSA during excessive alcohol consumption reflects the changes in sialylated glycoproteins in the sera. On the other hand, chronic ethanol consumption increases the desialylation rate of many serum glycoproteins. ...
Blume Astrid - - 2007
Using STD NMR experiments, we have studied the binding epitopes of p-nitrophenyl glycosides of sialic acid and analogs thereof when bound to Trypanosoma cruzi trans-sialidase (TSia). Time-dependent NMR spectra yielded data on the rate of substrate hydrolysis in comparison to sialic acid transfer. Our experiments clearly demonstrate that shortening of ...
Patel Dhara A - - 2007
beta-Amyloid (Abeta) is the primary protein component of senile plaques in Alzheimer's disease and is believed to be associated with neurotoxicity in the disease. We and others have shown that Abeta binds with relatively high affinity to clustered sialic acid residues on cell surfaces and that removal of cell surface ...
Pabst Martin - - 2007
Analysis of the numerous possible, often isobaric structures of protein-bound oligosaccharides calls for a high-performance two-dimensional method that combines liquid chromatography's ability to separate isomers and mass spectrometry's ability to determine glycan composition. Here we investigate the usefulness of porous graphitic carbon columns coupled to ESI-MS for the separation of ...
Quaggin Susan E - - 2007
A new study by Galeano and colleagues in this issue of the JCI reports the first glomerular disease caused by a genetic defect in sialic acid biosynthesis (see the related article beginning on page 1585). Mice that harbor mutations in the Gne/Mnk gene produce lower amounts of sialic acid, suffer ...
Lundgren Benjamin R - - 2007
Sialic acid is the terminal sugar found on most glycoproteins and is crucial in determining serum half-life and immunogenicity of glycoproteins. Sialic acid analogs are antiviral therapeutics as well as crucial tools in bacterial pathogenesis research, immunobiology and development of cancer diagnostic imaging. The scarce supply of sialic acid hinders ...
Ogasawara Yuki - - 2007
In this work, we examined the antioxidant role of mucin, a typical sialic acid containing high-molecular weight glycoprotein. The function of mucin as a hydroxyl radical (.OH) scavenger was characterized using bovine submaxillary gland mucin (BSM). Non-treated BSM effectively protected DNA from the attack of .OH; however, desialylated BSM lost ...
Shelke Sachin V - - 2007
The trisaccharide substructure 13 of the ganglioside GQ1balpha shows a remarkable affinity for the myelin-associated glycoprotein (MAG). In the search for structurally simplified and pharmacokinetically improved mimics of 13, sialosides with modifications at the reducing and non-reducing end were synthesized. The biological evaluation of mimics 12a-o was performed in a ...
Yamakawa Nao - - 2007
Sulfated sialic acid (SiaS) is a unique sialic acid (Sia) derivative in which an additional anionic group is attached to a carboxylated monosaccharide. Very little is known about the occurrence and biologic function of SiaS, due to the limitations of analytical methods to detect it in minute amounts. In this ...
Go Shinji - - 2007
Hypoxia is a common characteristic of locally advanced tumors and cancer cells of high invasiveness and metastasis. We first demonstrate that hypoxic culture of human cancer HeLa, LS174T, and Caco-2 cells enhances the de novo synthesis of free sialic acids including deaminoneuraminic acid (Kdn), a unique sialic acid. Hypoxic cultures ...
Lindberg Gunnar - - 2007
Deficit sialylation of vascular endothelium, circulating cells and macromolecules has been associated with the development of atherosclerosis. On the other hand, an elevated serum level of sialic acid is a long-lasting marker of atherosclerosis and complications from atherosclerosis. One may speculate that the inverse associations with atherosclerosis risk are due ...
Liu Xin - - 2007
A simple and rapid "one-pot" methylation method to esterify sialic acids and construct a permanent charge was developed for N-linked glycan analysis, which combined complete nonspecific proteolytic digestion and methylation. A mixture of Asn-glycans prepared from Pronase E digestion of the glycoprotein was passed through a cation-exchange column to convert ...
Hanashima Shinya - - 2007
[reaction: see text] The ubiquity of the sialic acid alpha(2-3) galactose linkage in oligosaccharides of biological relevance necessitates a building block for the incorporation of this motif into oligosaccharides prepared by modular synthesis. The linear synthesis of the sialyl Lewis X tumor-associated antigen (1) has been accomplished in good yield ...
Takahata Masahiko - - 2007
Sialic acid, which is located at the end of the carbohydrate moiety of cell surface glycoconjugates, is involved in many biologic responses, such as intercellular reactions and virus-cell fusion, especially in hematopoietic cells. Here we provide experimental evidence that the sialic acid of cell surface glycoconjugates has a role in ...
Tzanakakis G N - - 2007
N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the dominant sialic acids (Sia) in mammals usually found in the non-reducing terminal of oligosaccharide side chains in glycoproteins and glycolipids. Their expression and distribution pattern have been correlated both with the malignant phenotype and tumor grade of human cancers. The aim ...
Vionnet Justine - - 2007
Escherichia coli K92 produces a capsular polysialic acid with alternating alpha2,8 alpha2,9 NeuNAc linkages. This polysaccharide is cross-reactive with the neuroinvasive pathogen Neisseria meningitidis Group C. The K92 polysialyltransferase (PST) catalyzes the synthesis of the polysialic acid with alternating linkages by the transfer of NeuNAc from CMP-NeuNAc to the nonreducing ...
Byrne Barry - - 2007
Sialic acids are structurally diverse molecules that have important roles in the physiological reactions and characteristics of prokaryotes and eukaryotes. These include the ability to mask epitopes on underlying glycan chains and to repulse negatively charged moieties. Here, we describe the metabolism and immunological relevance of sialic acids and outline ...
Parsons C Lowell - - 2007
OBJECTIVES: Tamm-Horsfall protein (THP) from normal urine has been shown to protect against the cytotoxic effects of toxic urinary cations (TFs) in vivo and in vitro. This study investigated the effect of desialylation on the cytoprotective activity of THP. METHODS: From pooled 24-hour urine specimens from healthy individuals, both TFs ...
Lrhorfi L Aicha - - 2007
The O-acetylation of sialic acids in various positions is a frequent modification of these residues in glycoproteins and glycolipids of higher animals and some bacteria. Sialic acid O-acetylation is involved in the regulation of many cell biological and pathophysiological events. Since the properties and the structural and molecular genetic aspects ...
Martín María J - - 2007
The developing human brain requires high amounts of sialic acids. While human milk is very rich in sialic acids, cow's milk based infant formulas provide lower amounts of sialic acids, and sialic acids are absent in soy milk based formulas. This has prompted interest in the supplementation of formulas with ...
Marzouk Sayed A M - - 2007
This paper describes the first report on the development, characterization, and applications of a prototype amperometric biosensor for free sialic acid (SA). The sensor was constructed by the coimmobilization of two enzymes, i.e., N-acetylneuraminic acid aldolase and pyruvate oxidase, on a polyester microporous membrane, which was then mounted on top ...
Valencia Julio C - - 2007
Pmel17 is a melanocyte/melanoma-specific protein that is essential for the maturation of melanosomes to form mature, fibrillar, and pigmented organelles. Recently, we reported that the less glycosylated form of Pmel17 (termed iPmel17) is sorted via the plasma membrane in a manner distinct from mature Pmel17 (termed mPmel17), which is sorted ...
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