TY - JOUR. T1 - NIST interlaboratory study on glycosylation analysis of monoclonal antibodies. T2 - comparison of results from diverse analytical methods. AU - De Leoz, Maria Lorna A.. AU - Duewer, David L.. AU - Fung, Adam. AU - Liu, Lily. AU - Yau, Hoi Kei. AU - Potter, Oscar. AU - Staples, Gregory O.. AU - Furuki, Kenichiro. AU - Frenkel, Ruth. AU - Hu, Yunli. AU - Sosic, Zoran. AU - Zhang, Peiqing. AU - Altmann, Friedrich. AU - Grünwald-Grube, Clemens. AU - Shao, Chun. AU - Zaia, Joseph. AU - Evers, Waltraud. AU - Pengelley, Stuart. AU - Suckau, Detlev. AU - Wiechmann, Anja. AU - Resemann, Anja. AU - Jabs, Wolfgang. AU - Beck, Alain. AU - Froehlich, John W.. AU - Huang, Chuncui. AU - Li, Yan. AU - Liu, Yaming. AU - Sun, Shiwei. AU - Wang, Yaojun. AU - Seo, Youngsuk. AU - An, Hyun Joo. AU - Reichardt, Niels Christian. AU - Ruiz, Juan Echevarria. AU - Archer-Hartmann, Stephanie. AU - Azadi, Parastoo. AU - Bell, Len. AU - Lakos, Zsuzsanna. AU - An, Yanming. AU - Cipollo, John F.. AU - ...
Abstract. Many West Nile (WN) virus isolates associated with significant outbreaks possess a glycosylation site on the envelope (E) protein. E-protein glycosylated variants of New York (NY) strains of WN virus are more neuroinvasive in mice than the non-glycosylated variants. To determine how E protein glycosylation affects the interactions between WN virus and avian hosts, we inoculated young chicks with NY strains of WN virus containing either glycosylated or non-glycosylated variants of the E protein. The glycosylated variants were more virulent and had higher viremic levels than the non-glycosylated variants. The glycosylation status of the variant did not affect viral multiplication and dissemination in mosquitoes in vivo. Glycosylated variants showed more heat-stable propagation than non-glycosylated variants in mammalian (BHK) and avian (QT6) cells but not in mosquito (C6/36) cells. Thus, E-protein glycosylation may be a requirement for efficient transmission of WN virus from avian hosts to
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The site-specific glycosylation of soluble recombinant variants of human and rat CD4 (sCD4) expressed in Chinese hamster ovary (CHO) cells has been characterized. The presence of identical oligosaccharides at the conserved glycosylation site in domain 3 of rat and human sCD4 and the greater abundance of oligomannose and hybrid type glycans at the non-conserved glycosylation site of rat sCD4 clearly indicate that the protein structure influences oligosaccharide processing. Comparisons of rat sCD4 glycopeptides with mutant molecules with only single glycosylation sites and with a truncated form containing only the two NH2-terminal domains, indicate that independent processing occurs at each glycosylation site and that domain interactions can also affect oligosaccharide processing. These and other analyses of sCD2 expressed in CHO cells and Thy-1 purified from various tissues suggest that the diversity of oligosaccharide structures on a protein is regulated by the location of the glycosylation sites and
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Glycosylation in S2 cells is very similar to that of SF9, Sf21, and High Five cells. The nature of Drosophila N-linked glycosylation is less complex than mammalian glycosylation - it is generally of the paucimannose type and is not trimmed and sialylated.. O-linked glycosylation is similar, although not identical, to that obtained in mammalian cells. However, human glycosylation profiles are difficult to obtain, also glycosylation from CHO and HEK293 differ from human glycosylation. Human O-glycosylation can be divided into N-acetylGalactosamine linked (mucin type), N-acetylGlucosamine lined (O-GlcNAc type) and xylose linked (proteoglycans) families. The most abundant form is the mucin type, while O-GlcNac has only been found for cytoplasmic and nuclear proteins, the proteoglycans are of less interest here.. In CHO cells, O-glycosylation results in terminally sialated mucin type glycans, with a low percentage core-1 structure (T-antigen) reported. In Drosophila S2, cell O-glycosylation is less ...
N-linked glycosylation has a profound effect on the proper folding, oligomerization and stability of glycoproteins. These glycans impart many properties to proteins that may be important for their proper functioning, besides having a tendency to exert a chaperone-like effect on them. Certain glycosylation sites in a protein however, are more important than other sites for their function and stability. It has been observed that some N-glycosylation sites are conserved over families of glycoproteins over evolution, one such being the tyrosinase related protein family. The role of these conserved N-glycosylation sites in their trafficking, sorting, stability and activity has been examined here. By scrutinizing the different glycosylation sites on this family of glycoproteins it was inferred that different sites in the same family of polypeptides can perform distinct functions and conserved sites across the paralogues may perform diverse functions.. ...
Production of the soluble portion of the transferrin receptor (sTFR) by baby hamster kidney (BHK) cells is described, and the effect of glycosylation on the biological function of sTFR is evaluated for the first time. The sTFR (residues 121−760) has three N-linked glycosylation sites (Asn251, Asn317, and Asn727). Although fully glycosylated sTFR is secreted into the tissue culture medium (∼40 mg/L), no nonglycosylated sTFR could be produced, suggesting that carbohydrate is critical to the folding, stability, and/or secretion of the receptor. Mutants in which glycosylation at positions 251 and 727 (N251D and N727D) is eliminated are well expressed, whereas production of the N317D mutant is poor. Analysis by electrospray ionization mass spectrometry confirms dimerization of the sTFR and the absence of the carbohydrate at the single site in each mutant. The effect of glycosylation on binding to diferric human transferrin (Fe_2 hTF), an authentic monoferric hTF with iron in the C-lobe ...
A majority of all biologically active proteins are glycosylated and various diseases have proven to correlate with alterations in protein glycosylation. Sensitive identification of different glycoprotein glycoforms is therefore of great diagnostic value. Here we describe a method with potential for glycoprotein profiling, based on lectins as capture probes immobilized on particulate substrates in the nm-range. The nanoparticles present high concentrations of attachment sites for specific ligands and cause minimal steric hindrance to binding. In the present model study the mannose-binding lectin ConA has been coupled to polystyrene nanoparticles via a poly(ethyleneoxide) linker which protects the protein conformation and activity and prevents unspecific protein adsorption. The ConA-coated particles are accommodated at different spots on the analytical surface via oligonucleotide linkage. This attachment, which relies on the hybridization of complementary oligonucleotides, allows firm fixation of ...
HIV-1 envelope glycoprotein (Env) is the sole target for broadly neutralizing antibodies (bnAbs) and the focus for design of an antibody-based HIV vaccine. The Env trimer is covered by ∼90N-linked glycans, which shield the underlying protein from immune surveillance. bNAbs to HIV develop during infection, with many showing dependence on glycans for binding to Env. The ability to routinely assess the glycan type at each glycosylation site may facilitate design of improved vaccine candidates. Here we present a general mass spectrometry-based proteomics strategy that uses specific endoglycosidases to introduce mass signatures that distinguish peptide glycosites that are unoccupied or occupied by high-mannose/hybrid or complex-type glycans. The method yields ,95% sequence coverage for Env, provides semi-quantitative analysis of the glycosylation status at each glycosite. We find that most glycosites in recombinant Env trimers are fully occupied by glycans, varying in the proportion of ...
Glycosylation, or the attachment of glycans (sugars) to proteins, is the most abundant post-translational modification in nature and plays a pivotal role in protein folding and activity. Glycans are involved in almost every human disease and biological process. Glycosylation is also important in biotechnology; about 70% of protein therapeutics approved or in development are glycosylated. By merging bottom-up engineering design principles with innovative molecular biology methodologies in a cell-free environment, we seek to create a simplified framework for studying and engineering glycosylation. Our envisioned platform will broaden the glycoengineering toolkit, facilitate discovery of the structural and functional consequences of glycan attachment, and enable a new era of applications in glycoprotein therapeutics and conjugate vaccines.. ...
Flavocytochrome b558 of the NADPH oxidase which generates superoxide in phagocytic cells, is a α1β1 heterodimer of gp91phox and p22phox, which together form a membrane-spanning electron-transport chain that transfers electrons from NADPH in the cytosol to oxygen. The C-terminal portion of gp91phox is a member of the ferredoxin-NADP+ reductase family of reductases. Little is known of the organization of the N-terminal section of this molecule, which is associated with the two haem structures. It is N-glycosylated, and site-directed mutagenesis has been used to eliminate the five potential N-linked glycosylation consensus sites. Mutated cDNAs were expressed in vitro. This approach provided evidence for glycosylation of residues Asn131, Asn148 and Asn239, but not of Asn96 and Asn429.. ...
Site-directed mutagenesis has been used to remove 15 of the 18 potential N-linked glycosylation sites, in 16 combinations, from the human exon 11-minus receptor isoform. The three glycosylation sites not mutated were asparagine residues 25, 397 and 894, which are known to be important in receptor biosynthesis or function. The effects of these mutations on proreceptor processing into α and β subunits, cell-surface expression, insulin binding and receptor autophosphorylation were assessed in Chinese hamster ovary cells. The double mutants 16+78, 16+111, 16+215, 16+255, 337+418, the triple mutants 295+337+418, 295+418+514, 337+418+514 and 730+743+881 and the quadruple mutants 606+730+743+881 and 671+730+743+881 seemed normal by all criteria examined. The triple mutant 16+215+255 showed only low levels of correctly processed receptor on the cell surface, this processed receptor being autophosphorylated in response to insulin. The quadruple mutant 624+730+743+881 showed normal processing and ligand ...
Kathrin Stavenhagen: Glycopeptide analysis remains challenging because of its sample heterogeneity resulting from the degree of glycosylation site occupancy (macroheterogeneity) and the different glycoforms attached to individual glycosylation sites (microheterogeneity).. With respect to the latter one, qualitative site-specific glycosylation information of glycoproteins can be obtained by unspecific protease treatment resulting in small amino acid stretches carrying the glycan. This improves determination of the glycosylation sites. However, detecting these glycopeptides by 1D-LC-ESI-MS/MS is challenging due to insufficient or irreversible retention on the stationary phase and thus multiple analyses with different LC-setups are required. Since biological sample amounts are usually limited, methods for acquiring comprehensive information in a single run are necessary.. To obtain qualitative information of the glycosylation site we set up an integrated C18-porous graphitized carbon ...
Abnormal glycosylation is a hallmark of many cancers that contributes to tumor growth and invasion. There are many protein receptors that are regulated abnormally in cancer due to mutations and/or alterations in glycosylation. Studies to link specific glycosylation changes to signaling outcomes have primarily focused on studies of individual receptors or specific pathways.
The structure of N-linked glycosylation is a very important quality attribute for therapeutic monoclonal antibodies. Different carbon sources in cell culture media, such as mannose and galactose, have been reported to have different influences on the glycosylation patterns. Accurate prediction and control of the glycosylation profile are important for the process development of mammalian cell cultures. In this study, a mathematical model, that we named Glycan Residues Balance Analysis (GReBA), was developed based on the concept of Elementary Flux Mode (EFM), and used to predict the glycosylation profile for steady state cell cultures. Experiments were carried out in pseudo-perfusion cultivation of antibody producing Chinese Hamster Ovary (CHO) cells with various concentrations and combinations of glucose, mannose and galactose. Cultivation of CHO cells with mannose or the combinations of mannose and galactose resulted in decreased lactate and ammonium production, and more matured glycosylation ...
Following the footsteps of genomics and proteomics, recent years have witnessed the growth of large-scale experimental methods in the field of glycomics. In parallel, there has also been growing interest in developing Systems Biology based methods to study the glycome. The combined goals of these endeavors is to identify glycosylation-dependent mechanisms regulating human physiology, check points that can control the progression of pathophysiology, and modifications to reaction pathways that can result in more uniform biopharmaceutical processes. In these efforts, mathematical models of N- and O-linked glycosylation have emerged as paradigms for the field. While these are relatively few in number, nevertheless, the existing models provide a basic framework that can be used to develop more sophisticated analysis strategies for glycosylation in the future. The current review surveys these computational models with focus on the underlying mathematics and assumptions, and with respect to their ...
Two urea transporters, UT-A1 and UT-A3, are expressed in the kidney terminal inner medullary collecting duct (IMCD) and are important for the production of concentrated urine. UT-A1, as the largest isoform of all UT-A urea transporters, has gained much attention and been extensively studied; however, the role and the regulation of UT-A3 are less explored. In this study, we investigated UT-A3 regulation by glycosylation modification. A site-directed mutagenesis verified a single glycosylation site in UT-A3 at Asn279. Loss of the glycosylation reduced forskolin-stimulated UT-A3 cell membrane expression and urea transport activity. UT-A3 has two glycosylation forms, 45 and 65 kDa. Using sugar-specific binding lectins, the UT-A3 glycosylation profile was examined. The 45-kDa form was pulled down by lectin concanavalin A (Con A) and Galant husnivalis lectin (GNL), indicating an immature glycan with a high amount of mannose (Man), whereas the 65-kDa form is a mature glycan composed of ...
Two urea transporters, UT-A1 and UT-A3, are expressed in the kidney terminal inner medullary collecting duct (IMCD) and are important for the production of concentrated urine. UT-A1, as the largest isoform of all UT-A urea transporters, has gained much attention and been extensively studied; however, the role and the regulation of UT-A3 are less explored. In this study, we investigated UT-A3 regulation by glycosylation modification. A site-directed mutagenesis verified a single glycosylation site in UT-A3 at Asn279. Loss of the glycosylation reduced forskolin-stimulated UT-A3 cell membrane expression and urea transport activity. UT-A3 has two glycosylation forms, 45 and 65 kDa. Using sugar-specific binding lectins, the UT-A3 glycosylation profile was examined. The 45-kDa form was pulled down by lectin concanavalin A (Con A) and Galant husnivalis lectin (GNL), indicating an immature glycan with a high amount of mannose (Man), whereas the 65-kDa form is a mature glycan composed of ...
In this study, we examined the potential N-glycosylation sites of RCL, and then discussed the functional significance of N-glycosylation on its secretion and enzymatic properties. RCL has four potential glycosylation sites in its gene sequence, three of which lie in the prosequence and the fourth of which is in the mature sequence (Figure 1B). Although the potential N-glycosylation sites of a protein can be predicted from the consensus sequence Asn-Xaa-Ser/Thr, not all such sites are fully occupied [33]. When RCL was expressed in P. pastoris, its N-terminal was truncated by Kex2. Thus, the three potential glycosylation sites in its prosequence were removed and only one glycosylation site at N-263 was retained in the truncated lipase r27RCLC (Figure 1). Enzymatic deglycosylation, which removed both high-mannose, hybrid-and complex-type N-linked glycans, was performed using glycosidases to investigate whether the potential glycosylation sites were glycosylated or not [3]. Endo Hf cleaved within ...
TY - JOUR. T1 - Nutritional therapies in congenital disorders of glycosylation (CDG). AU - Witters, Peter. AU - Cassiman, David. AU - Morava-Kozicz, Eva. PY - 2017/11/1. Y1 - 2017/11/1. N2 - Congenital disorders of glycosylation (CDG) are a group of more than 130 inborn errors of metabolism affecting N-linked, O-linked protein and lipid-linked glycosylation. The phenotype in CDG patients includes frequent liver involvement, especially the disorders belonging to the N-linked protein glycosylation group. There are only a few treatable CDG. Mannose-Phosphate Isomerase (MPI)-CDG was the first treatable CDG by high dose mannose supplements. Recently, with the successful use of D-galactose in Phosphoglucomutase 1 (PGM1)-CDG, other CDG types have been trialed on galactose and with an increasing number of potential nutritional therapies. Current mini review focuses on therapies in glycosylation disorders affecting liver function and dietary intervention in general in N-linked glycosylation disorders. We ...
Looking for online definition of protein glycosylation in the Medical Dictionary? protein glycosylation explanation free. What is protein glycosylation? Meaning of protein glycosylation medical term. What does protein glycosylation mean?
In the field of biochemistry, O-linked glycosylation is the attachment of a sugar molecule to an oxygen atom in an amino acid residue in a protein. O-linked glycosylation is a form of glycosylation that occurs in the Golgi apparatus in eukaryotes. It also occurs in archaea and bacteria. O-linked glycosylation occurs at a later stage during protein processing, probably in the Golgi apparatus. This is the addition of N-acetyl-galactosamine to serine or threonine residues by the enzyme UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase (EC number 2.4.1.41), followed by other carbohydrates (such as galactose and sialic acid). This process is important for certain types of proteins such as proteoglycans, which involves the addition of glycosaminoglycan chains to an initially unglycosylated proteoglycan core protein. These additions are usually serine O-linked glycoproteins, which seem to have one of two main functions. One function involves secretion to form components of ...
Advanced Glycosylation End Products: Products derived from the nonenzymatic reaction of glucose and proteins in vivo that exhibit a yellow-brown pigmentation and an ability to participate in protein-protein cross-linking. These substances are involved in biological processes relating to protein turnover and it is believed that their excessive accumulation contributes to the chronic complications of diabetes mellitus.
Highlights: •Down-regulating FUT9 and ST3Gal4 expression blocks L1-induced neuronal differentiation of ESCs. •Up-regulating FUT9 and ST3Gal4 expression in L1-ESCs depends on the activation of PLCγ. •L1 promotes ESCs to differentiate into neuron through regulating cell surface glycosylation. -- Abstract: Cell recognition molecule L1 (CD171) plays an important role in neuronal survival, migration, differentiation, neurite outgrowth, myelination, synaptic plasticity and regeneration after injury. Our previous study has demonstrated that overexpressing L1 enhances cell survival and proliferation of mouse embryonic stem cells (ESCs) through promoting the expression of FUT9 and ST3Gal4, which upregulates cell surface sialylation and fucosylation. In the present study, we examined whether sialylation and fucosylation are involved in ESC differentiation through L1 signaling. RNA interference analysis showed that L1 enhanced differentiation of ESCs into neurons through the upregulation of FUT9 and ...
TY - JOUR. T1 - Nonenzymatic glycosylation and the pathogenesis of diabetic complications. AU - Brownlee, M.. AU - Vlassara, H.. AU - Cerami, A.. PY - 1984. Y1 - 1984. N2 - Glucose chemically attaches to proteins and nucleic acids without the aid of enzymes. Initially, chemically reversible Schiff base and Amadori product adducts form in proportion to glucose concentration. Equilibrium is reached after several weeks, however, and further accumulation of these early nonenzymatic glycosylation products does not continue beyond that time. Subsequent reactions of the Amadori product slowly give rise to nonequilibrium advanced glycosylation end-products which continue to accumulate indefinitely on longer-lived molecules. Excessive formation of both types of nonenzymatic glycosylation product appears to be the common biochemical link between chronic hyperglycemia and a number of pathophysiologic processes potentially involved in the development of long-term diabetic complications. The major biological ...
The N-linked glycosylation in recombinant monoclonal antibodies (mAb) occurs at Asn297 on the Fc region in the CH2 domain. Glycosylation heterogeneities have been well documented to affect biological activities such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) through their interaction with Fc-receptors. Hence, it is critical to monitor and characterize the N-linked glycosylation profile in a therapeutic protein such as a mAb for product consistency. In one approach, the glycans are first released from the mAb using an enzyme specific digestion, such as Protein N-Glycosidase F (PNGase) and subsequently they are labeled using a fluorophore, for example, 8-aminopyrene-1,3,6-trisulfonic acid (APTS) . Here we have applied this approach and used Capillary Electrophoresis with Laser-Induced Fluorescence detection (CE-LIF) to analyze a recombinant mAb produced in murine myeloma (NS0) cells. The technique provides short analysis times, efficient separations, and
Congenital disorder of glycosylation type 2A (CDG 2A) is a part of a group of rare inherited conditions that are present at birth (congenital) and involve defects in the glycosylation process. Glycosylation involves the joining of sugars and proteins (to form glycoproteins) by enzymes (proteins that function to convert specific substances in the body) in the cells of our bodies. These sugars (glycans) must be properly attached to specific proteins in the cells in order for the cells to function correctly. Due to the many functions of these glycoproteins throughout the body, if an error occurs in one of the many steps of the process, a wide variety of health problems may occur beginning in infancy. Symptoms can include psychomotor delays (movement, coordination, dexterity), mental retardation, and distinct physical features including thin lips, large gums, low-set rotated ears, and small head circumference. Some affected individuals may have gastrointestinal problems like diarrhea and reflux. ...
The interactions of B7-1 with CD28 and CTLA-4 modulate the course of human immune responses, making B7-1 an important target for developing structure-based therapeutics. B7-1 is, however, one of the most heavily glycosylated proteins found at the leukocyte cell surface, complicating the structural analysis of this molecule. Methods for the production, crystallization and selenomethionine labelling of a soluble deglycosylated form of this molecule are described. The protein readily forms both tetragonal plate and bipyramidal crystals belonging to space groups I4(1)22, with unit-cell parameters a = b = 56.9, c = 298.7 A, and P4(1)22 (or P4(3)22), with unit-cell parameters a = b = 89.0, c = 261.9 A, respectively. The I4(1)22 and primitive crystal forms diffract to 2.7 and 3.5 A, respectively. Surface plasmon resonance-based assays indicate that the ligand-binding properties of sB7-1 are unaffected by deglycosylation. Since none of the methods relied on any special structural properties of sB7-1, it is
Protein instability remains the main factor limiting the development of protein therapeutics. The fragile nature (structurally and chemically) of proteins makes them susceptible to detrimental events during processing, storage, and delivery. To overcome this, proteins are often formulated in the solid-state which combines superior stability properties with reduced operational costs. Nevertheless, solid protein pharmaceuticals can also suffer from instability problems due to moisture sorption. Chemical protein glycosylation has evolved into an important tool to overcome several instability issues associated with proteins. Herein, we employed chemical glycosylation to stabilize a solid-state protein formulation against moisture-induced deterioration in the lyophilized state. First, we investigated the consequences of moisture sorption on the stability and structural conformation of the model enzyme α-chymotrypsin (α-CT) under controlled humidity conditions. Results showed that α-CT aggregates and
View Notes - Glycobiology_Course_lesson_4_diagnostics from WE BIBI000000 at Ghent University. Glycobiology Course IV Clinical diagnostics based on glycosylation Roland Contreras Nico Callewaert
TY - JOUR. T1 - Migration of keratinocytes is impaired on glycated collagen I. AU - Morita, Keisuke. AU - Urabe, Kazunori. AU - Moroi, Yoichi. AU - Koga, Tetsuya. AU - Nagai, Ryuji. AU - Horiuchi, Seiko. AU - Furue, Masutaka. PY - 2005/1. Y1 - 2005/1. N2 - Advanced glycation end products are the chemical modification of proteins induced by sugars in a hyperglycemic condition. Extracellular matrix proteins are prominent targets of nonenzymatic glycation because of their slow turnover rates. The aim of this study was to investigate the influence of nonenzymatic glycation of type I collagen on the migration of keratinocytes. The migration of keratinocytes was dramatically promoted on native type I collagen-coated dishes compared with that on uncoated dishes. When type collagen was glycated with glycolaldehyde, large amounts of advanced glycation end products were produced; the glycated collagen I-coated dishes did not promote the migration of keratinocytes. Glycated collagen I did not affect the ...
Looking for online definition of glycosylation in the Medical Dictionary? glycosylation explanation free. What is glycosylation? Meaning of glycosylation medical term. What does glycosylation mean?
The primary hypothesis in this study is that adding simple milk sugar (galactose) to the diet of Congenital Disorders of Glycosylation patients will normalize the metabolic abnormalities. The secondary hypothesis posits that galactose intervention in Congenital Disorders of Glycosylation patients will normalize specific physiological biomarkers of protein glycosylation that can be utilized for future phase II/III trial development. The knowledge gained from the investigation of these two aims will help the investigators learn more about the disrupted metabolic mechanism of this disease and should lead to the identification of new disease biomarkers that can be used to evaluate clinical efficacy in future therapeutic trials.. Over a two-year period, the investigators will enroll patients diagnosed with Congenital Disorders of Glycosylation. The investigators propose to administer oral galactose supplementation for a period of 18 weeks in increasing dose to assess its effectiveness at normalizing ...
Human immunodeficiency virus type 1 (HIV-1) enters cells through the chemokine receptors CCR5 (R5 virus) and/or CXCR4 (X4 virus). Loss of N-linked glycans and increased net charge of the third variable loop (V3) of the gp120 envelope glycoprotein have been observed to be important steps towards CXCR4 use. All reported sequences using CCR5 or CXCR4 exclusively, or using both, were gathered from the Los Alamos HIV Database and analysed with regard to the V3 N-linked glycosylation motifs (sequons) and charge. The V3 loop glycan had a sensitivity of 0·98 and a 0·92 positive predictive value in the context of CCR5 use. The difference from X4 was remarkable (P<10−12). Especially, the sequon motif NNT within the V3 loop was conserved in 99·2 % of the major clades. The results suggest a close association between the V3 loop glycan and CCR5 use and may provide new insight into HIV-1 tropism and help to improve phenotype-prediction models.
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Glycosyl ortho-alkynylbenzoates have emerged as a new generation of donors for glycosidation under the catalysis of gold(I) complexes such as Ph3PAuOTf and Ph3PAuNTf2 (Tf= trifluoromethanesulfonate). A wide variety of these donors, including 2-deoxy sugar and sialyl donors, are easily prepared and shelf stable. The glycosidic coupling yields with alcohols are generally excellent; even direct coupling with the poorly nucleophilic amides gives satisfactory yields. Moreover, excellent alpha-selective glycosylation with a 2-deoxy sugar donor and beta-selective sialylation have been realized. Application of the present glycosylation protocol in the efficient synthesis of a cyclic triterpene tetrasaccharide have further demonstrated the versatility and efficacy of this new method, in that a novel chemoselective glycosylation of the carboxylic acid and a new one-pot sequential glycosylation sequence have been implemented ...
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In this work different horseradish transformed lines (tumour and teratoma) were compared with control samples of leaf tissue in electrophoretic pattern of total cell proteins and their glycosylation. Emphasis was put on the comparison of these tissues in structure and composition of N-glycans of endoplasmic reticulum proteins. Despite its central metabolic role, the endoplasmic reticulum is also a starting point of protein glycosylation in eukaryotic cells. Two forms of protein glycosylation are known, N- and Oglycosylation. N-glycosylation is a major modification of proteins in plant cells. Plant N-glycans can be classified into four basic groups: high-mannose-type, complex-type, paucimannosidic-type and hybrid-type. N-glycosylation is a well described process whereas O-glycosylatin is not well characterized. Glycoproteins were separated on SDS-PAGE and subsequently transferred onto nitrocellulose membrane. Glycosylated proteins were detected with Con A. N-glycans were further characterized by ...
article{04b8831a-870b-4baa-b2ba-da9ecd197697, abstract = {Activated Factor V (FVa) functions as a membrane-bound cofactor to the enzyme factor Xa (FXa) in the conversion of prothrombin to thrombin, increasing the catalytic efficiency of FXa by several orders of magnitude. To map regions on FVa that are important for binding of FXa, site-directed mutagenesis resulting in novel potential glycosylation sites on FV was used as strategy. The consensus sequence for N-linked glycosylation was introduced at sites, which according to a computer model of the A-domains of FVa, were located at the surface of FV. In total, thirteen different regions on the FVa surface were probed, including sites that are homologous to FIXa-binding sites on FVIII. The interaction between the FVa variants and FXa and prothrombin were studied in a functional prothrombin activation assay, as well as in a direct binding assay between FVa and FXa. In both assays, the four mutants carrying a carbohydrate side chain at position ...
Samples can be sent for analysis by post or courier. Glycosylation is a stable modification and even in case of protein degradation, the corresponding glycoprofile can be determined. Depending on the analysis required, the proteins can be delivered at room temperature as lyophilised or precipitated samples, or on dry/wet ice when in solution. The results will be reported and discussed online, meaning no personal travel is required.. Analysis includes:. • Intact glycoprotein mass will be determined by MALDI TOF analysis using ultrafleXtreme MALDI TOF/TOF instrument (Bruker). The level of glycosylation can be estimated by comparison of the intact glycoprotein with its deglycosylated form.. • Analysis of N-glycoprofile includes protein denaturation, deglycosylation, isolation of released glycans with subsequent permethylation and analysis by MALDI TOF/TOF mass spectrometry (ultrafleXtreme, Bruker).. • The protein glycosylation sites will be determined by proteolytic cleavage, heavy atom ...
A glycosyl donor is a carbohydrate mono- or oligosaccharide that will react with a suitable glycosyl acceptor to form a new glycosidic bond. By convention, the donor is the member of this pair that contains the resulting anomeric carbon of the new glycosidic bond. The resulting reaction is referred to as a glycosylation or chemical glycosylation. In a glycosyl donor, a leaving group is required at the anomeric position. The simplest leaving group is the OH group that is naturally present in monosaccharides, but it requires activation by acid catalysis in order to function as leaving group (in the Fischer glycosylation). More effective leaving groups are in general used in the glycosyl donors employed in chemical synthesis of glycosides. Typical leaving groups are halides, thioalkyl groups, or imidates, but acetate, phosphate, and O-pentenyl groups are also employed. Natural glycosyl donors contain phosphates as leaving groups. The so-called armed-disarmed principle The concept of armed and ...
The selectin family of cell adhesion molecules mediates the tethering and rolling of leukocytes on blood vessel endothelium. It has been postulated that the molecular basis of this highly dynamic adhesion is the low affinity and rapid kinetics of selectin interactions. However, affinity and kinetic analyses of monomeric selectins binding their natural ligands have not previously been reported. Leukocyte selectin (L-selectin, CD62L) binds preferentially to O-linked carbohydrates present on a small number of mucin-like glycoproteins, such as glycosylation-dependent cell adhesion molecule-1 (GlyCAM-1), expressed in high endothelial venules. GlyCAM-1 is a soluble secreted protein which, following binding to CD62L, stimulates beta2-integrin-mediated adhesion of lymphocytes. Using surface plasmon resonance, we show that a soluble monomeric form of CD62L binds to purified immobilized GlyCAM-1 with a dissociation constant (Kd) of 108 microM. CD62L dissociates from GlyCAM-1 with a very fast dissociation rate
The hexosamine biosynthetic pathway, whose end product is UDP-N acetylglucosamine (UDP-GlcNAc), lies at the base of cellular glycosylation pathways, including glycosylation of lipids, formation of heparin sulfated proteoglycans, and N- and O-linked glycosylation of proteins. Forward genetic studies in Drosophila have revealed that mutations in genes encoding different enzymes of the hexosamine biosynthetic pathway result in reduction of UDP-GlcNAc to different extents, with a consequent disruption of distinct glycosylation pathways and developmental processes. A maternal and zygotic loss-of-function screen has identified mutations in nesthocker (nst), which encodes an enzyme in the hexosamine biosynthetic pathway. Embryos lacking maternal and zygotic nst gene products show defective O-GlcNAcylation of a fibroblast growth factor receptor (FGFR)-specific adaptor protein, which impairs FGFR-dependent migration of mesodermal and tracheal cells.. ...
The current study highlights a novel glycosylation-dependent mechanism that confers gemcitabine resistance by preventing DNA damage. Experimental procedures Cell culture MiaPaCa-2 and BxPC-3 cell lines were obtained from ATCC. increased gemcitabine sensitivity ratio, an indication of gemcitabine toxicity. Gemcitabine-resistant MiaPaCa-2 cells display higher ST6Gal-I levels than treatment-na?ve WEHI-9625 cells along with a reduced gemcitabine sensitivity ratio, suggesting that WEHI-9625 chronic chemotherapy selects for clonal variants with more abundant ST6Gal-I. Finally, we examined Suit2 PDAC cells and Suit2 derivatives with enhanced metastatic potential. Intriguingly, three metastatic and chemoresistant subclones, S2-CP9, S2-LM7AA, and S2-013, exhibit up-regulated ST6Gal-I relative to parental Suit2 cells. ST6Gal-I KD in S2-013 cells increases gemcitabine-mediated DNA damage, indicating that suppressing ST6Gal-I activity sensitizes inherently resistant cells to gemcitabine. Together, these ...
TY - JOUR. T1 - N-glycosylated proteins and distinct lipooligosaccharide glycoforms of Campylobacter jejuni target the human C-type lectin receptor MGL. AU - van Sorge, N.M.. AU - Bleumink, N.M.C.. AU - van Vliet, S.J.. AU - Saeland, E.. AU - van der Pol, W.L.. AU - van Kooyk, Y.. AU - van Putten, J.W.. PY - 2009. Y1 - 2009. U2 - 10.1111/j.1462-5822.2009.01370.x. DO - 10.1111/j.1462-5822.2009.01370.x. M3 - Article. C2 - 19681908. VL - 11. SP - 1768. EP - 1781. JO - Cellular Microbiology. JF - Cellular Microbiology. SN - 1462-5814. IS - 12. ER - ...
The addition of specific monosaccharides to the oligosaccharide can mask the special sequence and prevent its recognition by microbial toxins or antibodies. Intracellular targeting of proteins may also depend on the glycan structure associated with the protein as was demonstrated for lyosomal enzymes. 5). Expression of specific types of glycosylation on different glycoconjugates in different tissues at different times during development imply that these structures have diverse roles in the same organism. Further, each potential glycosylation site in a given glycoprotein population is fully, partially, or not at all occupied. In fact, an eukaryotic glycoprotein is not isolated as a single structural entity, but rather as a set of glycosylated variants of a common polypeptide, which are referred to as glycoforms [11, 13]. The particular glycosylation pattern of a protein is not random and uncontrolled and reflects the balance of all activities of that glycoprotein in a particular physiological ...
Berg, Tore Julsrud; Dahl-Jørgensen, Knut; Torjesen, Peter A.; Bucala, Richard & Hanssen, Kristian Folkvord (1996). Increased serum levels of Advanced glycosylation end products (AGEs) in children and adolescents with IDDM. Show summary Increased Serum levels of Advanced Glycosylation End products (AGEs) in Children and Adolescents with IDDM. TORE J. BERG, KNUT DAHL-JØRGENSEN*, PETER A. TORJESEN, RICK BUCALA*4, KRISTIAN F. HANSSEN, Oslo, Norway and Manhasset, NY.We have developed a sandwich fluoremetric-immunoassay for measuring AGEs in serum utilizing polyclonal antibodies made from rabbit immunized with AGE-RNase. Using this assay we have earlier shown that AGEs in serum predict the progression of morphological pathology in the kidney of diabetic patients with microalbuminuria. In the present study we aimed to investigate whether the serum levels of AGEs in a cohort of diabetic adolescent patients were different from normal subjects. IDDM patients (n=69) were compared with healthy ...

Results We discovered that ACPA-IgG from RA patients have a higher apparent molecular weight as compared to other IgG molecules including antibodies against recall antigens and other autoantibodies. This higher molecular weight was explained by the overrepresentation of N-linked glycans in the variable domain (Fab region) of ACPA-IgG. Detailed structural analysis of these glycans demonstrated that ACPA-IgG linked Fab glycans are complex-type biantennary N-glycans that differ from the conventional Fc-linked N-glycans by a high degree of sialylation, galactosylation, and fucosylation together with the presence of bisecting N-acetylglucosamine. Using recombinant ACPA-IgG monoclonal antibodies with and without Fab-glycans, we found that Fab-glycans modulate binding affinity of ACPA-IgG for citrullinated antigens. Finally, lectin-immunoblotting showed that ACPA Fab-glycans can bind to sialic acid-binding immunoglobulin-type lectins.. ...
Most subtypes of CDG are classified as disorders of N-glycosylation, which involves carbohydrates called N-linked oligosaccharides. These oligosaccharides are created in a specific order to create specific sugar trees, which are then attached to proteins on various cells. Disorders of N-glycosylation are due to an enzyme deficiency or other malfunction somewhere along the N-glycosylation pathway.. As long as the defect is not identified, disorders of N-glycosylation are subdivided into defects of oligosaccharide assembly and transfer (CDG-Ix) and defects in oligosaccharide trimming and processing that occur after they are bound to proteins (CDG-IIx). As soon as the defect in an individual patient is clarified, a CDG name is given according to the current nomenclature.. Disorders of N-glycosylation include:. PMM2-CDG - This disorder is the most common type of CDG. More than 700 individuals have been identified. The disorder can be broken down into three stages: infantile multisystem, ...
To determine whether the N-terminal hydrophobic sequence is also responsible for retention, the N-terminal 29 amino acids of cytochrome P450 2C1, with and without an additional 29 amino acids containing an N-glycosylation site, were fused to a soluble cytoplasmic protein, Escherichia coli $\beta$-galactosidase, or to a secreted protein, Escherichia coli alkaline phosphatase, and the hybrid proteins were expressed in COS1 cells and cellular localization was determined by subcellular fractionation, immunolocalization and the glycosylation state of the proteins. Both the $\beta$-galactosidase and alkaline phosphatase hybrid proteins were retained in the endoplasmic reticulum establishing that a specific sequence or property in the N-terminal 29 amino acids is responsible for ER retention. To further examine the possibility that retention of proteins with a large cytoplasmic domain is the default pathway, the cellular distributions of a series of P450 2C1 and EGFR chimeric proteins were examined. ...
Autor: Guillard, Mailys et al.; Genre: Zeitschriftenartikel; Im Druck veröffentlicht: 2009-09; Keywords: Glycosylation; Cutis laxa; V-ATPase; Congenital disorders of glycosylation; OMIM 219200; Apolipoprotein C III; Titel: Vacuolar H+-ATPase meets glycosylation in patients with cutis laxa
TY - JOUR. T1 - Role of glycosylation in the H-2-restricted cytolysis of virus-infected cells. AU - Black, P. L.. AU - Vitetta, E. S.. AU - Forman, J.. AU - Kang, C. Y.. AU - May, R. D.. AU - Uhr, J. W.. PY - 1981. Y1 - 1981. N2 - The role of the oligosaccharide portions of cell surface glycoproteins in the susceptibility of virus-infected cells to H-2-restricted cytolysis was investigated by using the antibiotic tunicamycin (TM). TM inhibits the addition of sugars to the polypeptides of glycoproteins. TM treatment of P 815 cells before and during infection with vesicular stomatitis virus (VSV) inhibited glycosylation of proteins and reduced by about 50% the lysis of infected P 815 cells by VSV-immune, H-2-identical killer cells. In contrast, TM treatment had a modest inhibitory effect on cytolysis of P 815 cells by alloimmune effector cells. TM treatment did not inhibit the surface expression of either H-2 or VSV glycoprotein. Thus, glycosylation of H-2 and/or viral glycoprotein is a ...
C-type lectins are important molecules of the innate immune system. These molecules, like surfactant protein D (SP-D) can recognize glycans on pathogens and neutralize these. Also influenza viruses are recognized by SP-D and their susceptibility to neutralization by SP-D is dependent on the number of N-linked glycosylation sites in the hemagglutinin in particular. Porcine SP-D displayed stronger neutralizing activity to human influenza A viruses than to swine influenza A viruses. Although viruses from these species differ with regard to the number of glycosylation sites in the hemagglutinin, the mechanism underlying the differential recognition by porcine SP-D is poorly understood. Here we investigated the molecular basis for the differential recognition of a seasonal H1N1 and a 2009 pandemic H1N1 virus by porcine SP-D. We demonstrated that the number and position of glycosylation sites determine viral susceptibility to the neutralizing activity of porcine SP-D. However, predicting the effect ...
TY - JOUR. T1 - Killing of Trypanosoma brucei by Concanavalin A. T2 - Structural basis of resistance in glycosylation mutants. AU - Acosta-Serrano, Alvaro. AU - Cole, Robert N. AU - Englund, Paul T.. PY - 2000/12/8. Y1 - 2000/12/8. N2 - Concanavalin A (Con A) kills procyclic (insect) forms of Trypanosoma brucei by binding to N-glycans on EP-procyclin, a major surface glycosyl phosphatidylinositol (GPI)-anchored protein which is rich in Glu-Pro repeats. We have previously isolated and studied two procyclic mutants (ConA 1-1 and ConA 4-1) that are more resistant than wild-type (WT) to Con A killing. Although both mutants express the same altered oligosaccharides compared to WT cells, ConA 4-1 is considerably more resistant to lectin killing than is ConA 1-1. Thus, we looked for other alterations to account for the differences in sensitivity. Using mass spectrometry, together with chemical and enzymatic treatments, we found that both mutants express types of EP-procyclin that are either poorly ...
BACKGROUND: Mesangial IgA1 deposition is characteristic of IgA nephropathy (IgAN). Structural abnormalities of the IgA1 glycoprotein may play a key role in its mesangial deposition, particularly the recently described abnormalities of O-glycosylation of the IgA1 hinge region. The mechanism of abnormal O-glycosylation has not yet been elucidated; it is not clear whether there is an alteration in the amino acid sequence of the hinge region, modifying the number of O-glycosylation sites available, or whether there is a post-translational defect in the glycosylation process. METHODS: The O-glycosylation of serum IgA1 from a series of patients with IgAN and matched controls was assessed by lectin binding assay. We then used dideoxy-sequencing of the PCR-amplified hinge region of the alpha1 heavy chain gene to compare the hinge region nucleotide sequence in IgAN and controls. We also compared cDNA transcripts of alpha1 hinge region mRNA to look for evidence for a transcriptional abnormality in IgAN. ...
I have a recombinant protein produced in the yeast Pichia pastoris that is partially glycosylated with O-linked sugar (it must be O-linked - there are no N-linked sites). I wish to remove the glycosylated protein from the non-glycosylated. I have tried using ConA-Sepharose (Pharmacia) and Glycine-Max (Sigma). Neither of these has appeared to bind. The ConA comes with instructions that have been followed. No instructions could be found for Gycine-MAx and Sigma were not forthcoming. Has anyone has experience with trying to purify O-linked sugars, with either of the above lectins, or using any other reagents, I would very much like to hear from you. Please reply to me by e-mail as I do not regularly read this newsgroup. Tim -- Tim Dudgeon British Biotech Phone: 0865 748747 FAX: 0865 717598 email: dudgeon at britbio.co.uk ...
N-glycans or asparagine-linked glycans are major constituents of glycoproteins in eukaryotes. N-glycans are covalently attached to asparagine with the consensus sequence of Asn-X-Ser/Thr by an N-glycosidic bond, GlcNAc b1- Asn. Biosynthesis of N-glycans begins on the cytoplasmic face of the ER membrane with the transferase reaction of UDP-GlcNAc and the lipid-like precursor P-Dol (dolichol phosphate) to generate GlcNAc a1- PP-Dol. After sequential addition of monosaccharides by ALG glycosyltransferases [MD:M00055], the N-glycan precursor is attached by the OST (oligosaccharyltransferase) complex to the polypeptide chain that is being synthesized and translocated through the ER membrane. The protein-bound N-glycan precursor is subsequently trimmed, extended, and modified in the ER and Golgi by a complex series of reactions catalyzed by membrane-bound glycosidases and glycosyltransferases. N-glycans thus synthesized are classified into three types: high-mannose type, complex type, and hybrid type. ...
Should you be thinking more about glycosylation? Glycosylation, which is the addition of carbohydrates to proteins or other molecules, plays a huge part in protein folding, protein stability, cell adhesion, cellular function and protection, recognition of self, pathogen invasion, and much more. From bacteria to yeast to mammals, it happens everywhere and it happens a lot. Yet in the light of biological research, it is often overlooked or even disregarded. This blog discusses a few of the many important roles for glycosylation in biology.
Traumatic spinal cord injury (SCI) results in disruption of tissue integrity leading to a loss of function. There has been minimal success in treating these injuries clinically, due to the inhibitory environment which develops over time. In this work, we study the glycosylation response to SCI in two models: Xenopus laevis is used to compare successful to failed regeneration, by comparing the response to injury pre- and post-metamorphosis, while we use a rat model to understand the pathophysiology of the injury and how this may be modified by treatment with an aligned collagen hydrogel. We hypothesise that glycosylation is altered in response to injury, that it has a role in determining the success of regeneration, and that biomaterial treatment can influence this glycosylation response. Complete transection was used to model SCI in pre- and post-metamorphic stages of Xenopus laevis and in adult rat. Collagen hydrogels with aligned or non-aligned fibres were placed at the transection site in the ...
To help the researchers and pharmaceutical partners with discovering the most effective therapeutic glycoprotein, Creative Biolabs provides solutions on glycosylation, the most widely applied posttranslational modification (PTM) approach to change protein function and measure the recombinant biopharmaceutical immunogenicity. Based upon the efficient glycoengineered expression platforms (glyco-engineered mammalian cell expression system, glyco-engineered pichia pastoris expression system, and glyco-engineered plant-based expression system), Creative Biolabs is fully competent to handle the requests of therapeutic glycoprotein development and glycoengineering of antibody/cell line.. Creative Biolabs has updated the generally applied mammalian cell expression with glyco-engineered Chinese hamster ovary (CHO) cells and glyco-engineered human embryonic kidney 293 (HEK293) cells for glycoprotein production, which can guarantee the natural folding and sugar chain composition of glycoprotein, and ...
METHOD FOR PRODUCING OXIDIZED GAMMA-GLUTAMYLCYSTEINE AND OXIDIZED GLUTATHIONE | USE OF METAL IONS FOR MODULATION OF PROTEIN GLYCOSYLATION PROFILES OF RECOMBINANT PROTEINS | SERUM ALBUMIN BINDING MOLECULES | METHODS FOR PRODUCING RECOMBINANT GLYCOPROTEINS WITH MODIFIED GLYCOSYLATION | Methods for producing polypeptides in enzyme-deficient mutants of fusarium venentatum |
IgG glycosylation is skewed toward proinflammatory G0 variants in healthy children, in particular during the first few years of life. This deviation is exaggerated in patients with JIA. The role for IgG glycan variation in immune function in children, including the predilection of JIA for early chil …
Sriram Neelamegham received grants to fund his research focused on developing a systems level understanding of cellular glycosylation processes, using a combination of mathematical modeling methods and experiments. Such work is important since glycans, or carbohydrates expressed on cells, either absolutely control or finely tune a number of biological processes in human during health and disease. The studies being pursued are thus important for biotechnology and medical research. Collaborators on the awards include Professor Jun Qu (Pharmaceutical Sciences), Michael Buck (Biochemistry), G. Ekin Atilla-Gokcumen (Chemistry) and Lara Mahal (Chemistry, New York University). ...
Sigma-Aldrich offers abstracts and full-text articles by [Erandi Lira-Navarrete, Matilde de Las Rivas, Ismael Compañón, María Carmen Pallarés, Yun Kong, Javier Iglesias-Fernández, Gonçalo J L Bernardes, Jesús M Peregrina, Carme Rovira, Pau Bernadó, Pierpaolo Bruscolini, Henrik Clausen, Anabel Lostao, Francisco Corzana, Ramon Hurtado-Guerrero].
CD24, also known as heat-stable antigen (HSA) in mice, is a small heavily glycosylated cell-surface protein that is linked to the membrane by a glycosyl-phosphatidylinositol (GPI-) anchor (Pierres et al., 1987; Kay et al., 1990; Alterman et al., 1990). Mouse CD24 has a protein core of 27 amino acids with seven potential glycosylation sites, whereas human CD24 consists of 31 amino acids with 16 potential O- and N-glycosylation sites. Owing to this extensive glycosylation, CD24 has mucin-like characteristics (reviewed by Kristiansen et al., 2004b).. CD24 is expressed in mouse hematopoietic cell subpopulations including B lymphocytes, the majority of thymocytes, erythrocytes and neutrophils. Because of its lineage-specific and developmentally regulated expression, CD24 was traditionally used as a differentiation marker for B- and T-cell ontogeny (Poncet et al., 1996; Egerton et al., 1990; Lu et al., 1998). Later studies revealed that CD24 is not exclusively expressed by hematopoietic cells but is ...