A standard Boyle International anaesthetic machine was modified to allow operation in either a co... more A standard Boyle International anaesthetic machine was modified to allow operation in either a continuous flow or a drawover mode. This was achieved by fitting a valve in the backbar which allows entrainment of air under drawover conditions. The details of the valve and modification are discussed and an evaluation of the machine in a Central African hospital is presented.
Scoring systems provide a means for comparing results, ensuring consistent standards and evaluati... more Scoring systems provide a means for comparing results, ensuring consistent standards and evaluating changes in therapy. The APACHE II system depends partly on the results of laboratory tests which are not normally available in Central Africa. The aim of this study was to develop a scoring system based only on clinical observations. Six hundred and twentyfour consecutive admissions to the intensive care unit (ICU) were allocated a clinical sickness score (CSS) according to pulse rate, blood pressure, respiration rate, urine output, Glasgow Coma Scale, temperature and age. CSS was significantly associated with outcome, there being no significant difference between actual and predicted outcomes calculated by logistic regression analysis. There was a significant difference between mean scores for survivors and non-survivors in all diagnostic groups except diabetes. The proportional change in score from admission was also significantly associated with outcome on each subsequent day in ICU. The CSS provides an objective measure of illness severity for critically ill patients in Africa.
Journal of the American Society For Mass Spectrometry, Jun 30, 2000
Analysis of commercial samples of chicken ovalbumin by reversed-phase high performance liquid chr... more Analysis of commercial samples of chicken ovalbumin by reversed-phase high performance liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) showed the presence of several other co-purifying glycoproteins. These were isolated, subjected to tryptic digestion, and two of them were identified as ovomucoid and chicken riboflavin binding-protein following database matching of the peptide masses obtained by MALDI. The N-linked glycans were released from the glycoproteins and their structures were examined by MALDI-MS in combination with exoglycosidase digestion. Ovalbumin was found to be glycosylated mainly with high-mannose and hybrid structures, consistent with profiles obtained on the intact glycoprotein by electrospray. The other glycoproteins contained mainly larger, complex glycans with up to five antennae, many of which had earlier been associated with ovalbumin. (J Am Soc Mass Spectrom 2000, 11, 564 -571)
It is now well established that hypogalactosylation of IgG is a molecular marker for rheumatoid a... more It is now well established that hypogalactosylation of IgG is a molecular marker for rheumatoid arthritis (RA). However, the mechanism for the alteration of the galactosylation status has not been resolved. We compared the galactosyltransferase activities of anti-CD19 selected peripheral B lymphocytes of healthy subjects and patients with RA using ovalbumin as the acceptor substrate. In addition, certain samples of lymphocytes were assayed after Epstein-Barr virus (EBV) transformation and, also, the ability of bovine milk galactosyltransferase to galactosylate IgG in vitro was examined. Our results indicate that there is a significant difference between the galactosyltransferase activities of rheumatoid and control peripheral B lymphocytes and that EBV transformation causes a variable increase (15-1225%) in galactosyltransferase activity, over that present in the peripheral B lymphocytes from which the transformed cells were derived. Also the ubiquitous "lactose synthetase" type galactosyltransferase (EC 2.4.1.38) will galactosylate normal native IgG at concentrations of 500 mU/ml in vitro. We conclude that there is no evidence from our study for an IgG specific galactosyltransferase and that galactosyltransferase is an enzyme that is aberrantly modulated in peripheral B lymphocytes and EBV transformed B lymphoblasts derived from patients with RA.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any fo... more All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.71.102-05/05/12,18:10:25) ... 192 Silicon Carbide and Related Materials 2000 ... 194 Silicon Carbide and Related Materials 2000 ... Silicon Carbide and Related Materials 2000 10.4028/www.scientific.net/MSF.353-356 ... Structural and Optical Properties of SiC Films Deposited on Si by DC Magnetron
Human monoclonal antibodies to the Rh D blood group antigen were produced by EBV-transformed B ce... more Human monoclonal antibodies to the Rh D blood group antigen were produced by EBV-transformed B cell lines grown in serum-free medium in low density (LD) static cultures or high density (HD) hollow fiber bioreactors. Glycosylation analysis of the purified IgG was determined by the binding of anti-GlcNAc monoclonal antibody (GN7) and by analysis of oligosaccharides released by hydrazinolysis. The LD MAbs had only trace levels of agalactosyl oligosaccharides (G0), the major species (> 70%) being digalactosyl structures (G2). The HD MAbs, by contrast, contained about 10% G0 and relatively high levels (over 50%) of monogalactosyl (G1) oligosaccharides. beta 1-4 galactosyltransferase activity in the LD cell lines was similar to that found previously for other EBV-transformed B cell lines. The predominant oligosaccharides of an IgG3 anti-D, BRAD-3, contained bisecting N-acetylglucosamine. In functional assays with Fc receptor (Fc gamma R) positive effector cells, the highly galactosylated LD form of BRAD-3 was more active than the HD form in monocyte (Fc gamma RI) and K cell (Fc gamma RIII) mediated lysis of erythrocytes in ADCC assays, although these preparations showed no difference in Fc gamma RI-mediated rosette formation with U937 cells. One MAb, JAC10, was over 10-fold less active than two other IgG1 MAbs, 2B6 and BRAD-5, at mediating lysis of erythrocytes by Fc gamma RIII+ K cells; differences in sialylation may have contributed to this heterogeneity.(ABSTRACT TRUNCATED AT 250 WORDS)
The IgE of sera from patients with a history of allergy to oranges (Citrus sinensis) bind a numbe... more The IgE of sera from patients with a history of allergy to oranges (Citrus sinensis) bind a number of proteins in orange extract, including Cit s 1, a germin-like protein. In the present study, we have analysed its immunological cross-reactivity and its molecular nature. Sera from many of the patients examined recognise a range of glycoproteins and neoglycoconjugates containing β1,2-xylose and core α1,3-fucose on their Nglycans. These reagents also inhibited the interaction of Cit s 1 with patients' sera, thus underlining the critical role of glycosylation in the recognition of this protein by patients' IgE and extending previous data showing that deglycosylated Cit s 1 does not possess IgE epitopes. In parallel, we examined the peptide sequence and glycan structure of Cit s 1 using mass spectrometric techniques. Indeed, we achieved complete sequence coverage of the mature protein as compared to the translation of an expressed sequence tag cDNA clone and demonstrated that the single N-glycosylation site of this protein carries oligosaccharides with xylose and fucose residues. Due to the presumed requirement for multivalency for in vivo allergenicity, our molecular data showing that Cit s 1 is monovalent as regards glycosylation and that the single N-glycan is the target of the IgE response to this protein, therefore, explain the immunological cross-reactive properties of Cit s 1 as well as its equivocal nature as a clinically-relevant allergen.
Mosquitoes are important vectors of parasitic and viral diseases with Anopheles gambiae transmitt... more Mosquitoes are important vectors of parasitic and viral diseases with Anopheles gambiae transmitting malaria and Aedes aegypti spreading yellow and Dengue fevers. Using two different approaches (solid-phase extraction and reversed-phase or hydrophilic interaction HPLC fractionation followed by MALDI-TOF MS or permethylation followed by NSI-MS), we examined the N-glycans of both A. gambiae and A. aegypti larvae and demonstrate the presence of a range of paucimannosidic glycans as well as bi- and tri-antennary glycans, some of which are modified with fucose or with sulphate or glucuronic acid residues; the latter anionic modifications were also found on N-glycans of larvae from another dipteran species (Drosophila melanogaster). The sulphate groups are attached primarily to core α-mannose residues (especially the α1,6-linked mannose), whereas the glucuronic acid residues are linked to non-reducing β1,3-galactose. Also, O-glycans were found to possess glucuronic acid and sulphate as we...
Molecular & cellular proteomics : MCP, Jan 22, 2015
The N-glycosylation of the model nematode Caenorhabiditis elegans has proven to be highly variabl... more The N-glycosylation of the model nematode Caenorhabiditis elegans has proven to be highly variable and rather complex; it is an example to contradict the existing impression that 'simple' organisms possess also a rather simple glycomic capacity. In previous studies in a number of laboratories, N-glycans with up to four fucose residues have been detected. However, although the linkage of three fucose residues to the N,N'-diacetylchitobiosyl core has been proven by structural and enzymatic analyses, the nature of the fourth fucose has remained uncertain. By constructing a triple mutant with deletions in the three genes responsible for core fucosylation (fut-1, fut-6 and fut-8), we have produced a nematode strain lacking products of these enzymes, but still retaining maximally one fucose residue on its N-glycans. Using mass spectrometry and HPLC in conjunction with chemical and enzymatic treatments as well as NMR, we examined a set of α-mannosidase-resistant N-glycans. With...
The locations of cytochrome c peroxidase and catalase activities in the two Gram-negative bacteri... more The locations of cytochrome c peroxidase and catalase activities in the two Gram-negative bacteria Pseudomonas stutzeri (N.C.I.B. 9721) and Paracoccus denitrificans (N.C.I.B. 8944) were investigated by the production of spheroplasts. In both species the cytochrome c peroxidase was predominantly periplasmic: 92% of total activity in Ps. stutzeri and 98% of nonmembrane-bound activity in Pa. denitrificans were found in this cellular compartment. In contrast, the catalase was mostly in the cytoplasmic fraction. Purification of the Pa. denitrificans cytochrome c peroxidase showed it to be the haem c-containing polypeptide of Mr 42,000 that has already been described by Bosma, Braster, Stouthamer & Van Versefeld [(1987) Eur. J. Biochem. 165, 665-670] but was not identified by them as a peroxidase. The visible-absorption spectra of the enzyme closely resemble those of cytochrome c peroxidase from Pseudomonas aeruginosa but the donor specificity is different, with the Pa. denitrificans enzy...
Baculovirus-mediated expression in insect cells has become well-established for the production of... more Baculovirus-mediated expression in insect cells has become well-established for the production of recombinant glycoproteins. Its frequent use arises from the relative ease and speed with which a heterologous protein can be expressed on the laboratory scale and the high chance of obtaining a biologically active protein. In addition to Spodoptera frugiperda Sf9 cells, which are probably the most widely used insect cell line, other mainly lepidopteran cell lines are exploited for protein expression. Recombinant baculovirus is the usual vector for the expression of foreign genes but stable transfection of - especially dipteran - insect cells presents an interesting alternative. Insect cells can be grown on serum free media which is an advantage in terms of costs as well as of biosafety. For large scale culture, conditions have been developed which meet the special requirements of insect cells. With regard to protein folding and post-translational processing, insect cells are second only...
Dolichol is utilized in vivo as an unusually large anchor on which the precursor for N-linked oli... more Dolichol is utilized in vivo as an unusually large anchor on which the precursor for N-linked oligosaccharides is assembled by a series of glycosyltransferases. The role of dolichol in enzyme substrate recognition is investigated. Thus the biosynthetic intermediate NN'-diacetylchitobiose was chemically linked to either dolichol or the much shorter fully saturated tetraisoprenoid phytanol. Both lipids were used as substrates by a recombinant, soluble beta-1,4-mannosyltransferase. beta-[3H]Mannosylated lipids from this reaction were then used as substrates for the subsequent mannosyltransferases from yeast or rat liver microsomes. It was found that both the dolichyl- and phytanyl-linked substrates were easily mannosylated to form Man5GlcNAc2, with some further mannosylation to Man7GlcNAc2 and Man9GlcNAc2 at low concentrations of lipid-linked substrate. It is concluded that dolichol is not necessary in vitro as part of the substrate for the mannosyltransferases in the biosynthetic ...
Carbohydrates are known as sources of immunological cross-reactivity of allergenic significance. ... more Carbohydrates are known as sources of immunological cross-reactivity of allergenic significance. In celery and in cypress pollen, the major allergens Api g 5 and Cup a 1 are recognised by antisera raised against anti-horseradish peroxidase and by patients' IgE which apparently bind carbohydrate epitopes; mass spectrometric analysis of the tryptic peptides and of their N-glycans showed the presence of oligosaccharides carrying both xylose and core alpha1,3-fucose residues. Core alpha1,3-fucose residues are also a feature of invertebrates: genetic and biochemical studies on the fruitfly Drosophila melanogaster, the parasitic trematode Schistosoma mansoni and the nematode worm Caenorhabditis elegans indicate that these organisms possess core alpha1,3-fucosyltransferases. Various experiments have shown that fucosyltransferases from both fly and worm are responsible in vivo and in vitro for the synthesis of N-glycans which cross-react with anti-horseradish peroxidase; thus, we can co...
Pristionchus pacificus is a free-living nematode increasingly used as an organism for comparison ... more Pristionchus pacificus is a free-living nematode increasingly used as an organism for comparison to the more familiar model Caenorhabditis elegans. In this study, we examined the N-glycans of this organism isolated after serial release with peptide:N-glycosidases F and A; after fluorescent labelling with 2-aminopyridine, chromatographic fractionation by three types of reversed-phase HPLC (with either classical C18, fused core C18 or alkylamide bonded phases) followed by mass spectrometric analyses revealed key features of its N-glycome. In addition to paucimannosidic and oligomannosidic glycans typical of invertebrates, N-glycans with two core fucose residues were detected. Furthermore, a range of glycans carrying up to three phosphorylcholine residues was observed whereas, unlike C. elegans, no tetrafucosylated N-glycans were detected. Structures with three fucose residues, unusual methylation of core α1,3-fucose or with galactosylated fucose motifs were found in low amounts; these...
N-glycans from the nematode Haemonchus contortus (barber pole worm), a parasite of sheep and catt... more N-glycans from the nematode Haemonchus contortus (barber pole worm), a parasite of sheep and cattle, were the first to be described to possess up to three fucose residues associated with the N,N'-diacetylchitobiosyl core, two being on the reducing-terminal proximal GlcNAc and one on the distal core GlcNAc residue. The assumption was that truncated glycans from this organism with three hexose residues have the composition Man3GlcNAc2Fuc1-3. In this study we have performed HPLC and MALDI-TOF MS/MS in combination with selected digestions of N-glycans from Haemonchus. A dominant trifucosylated Hex3HexNAc2Fuc3 glycan was modified not only with α1,6-fucose, but also with a proximal core α1,3-fucose and a galactosylated distal α1,3-fucose; thereby, only two of the hexose residues were mannose. Other N-glycans displayed galactosylation of the core α1,6-fucose, antennal fucosylation or modification with phosphorylcholine. Thus, the N-glycans of Haemonchus contain a number of potentially ...
A standard Boyle International anaesthetic machine was modified to allow operation in either a co... more A standard Boyle International anaesthetic machine was modified to allow operation in either a continuous flow or a drawover mode. This was achieved by fitting a valve in the backbar which allows entrainment of air under drawover conditions. The details of the valve and modification are discussed and an evaluation of the machine in a Central African hospital is presented.
Scoring systems provide a means for comparing results, ensuring consistent standards and evaluati... more Scoring systems provide a means for comparing results, ensuring consistent standards and evaluating changes in therapy. The APACHE II system depends partly on the results of laboratory tests which are not normally available in Central Africa. The aim of this study was to develop a scoring system based only on clinical observations. Six hundred and twentyfour consecutive admissions to the intensive care unit (ICU) were allocated a clinical sickness score (CSS) according to pulse rate, blood pressure, respiration rate, urine output, Glasgow Coma Scale, temperature and age. CSS was significantly associated with outcome, there being no significant difference between actual and predicted outcomes calculated by logistic regression analysis. There was a significant difference between mean scores for survivors and non-survivors in all diagnostic groups except diabetes. The proportional change in score from admission was also significantly associated with outcome on each subsequent day in ICU. The CSS provides an objective measure of illness severity for critically ill patients in Africa.
Journal of the American Society For Mass Spectrometry, Jun 30, 2000
Analysis of commercial samples of chicken ovalbumin by reversed-phase high performance liquid chr... more Analysis of commercial samples of chicken ovalbumin by reversed-phase high performance liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) showed the presence of several other co-purifying glycoproteins. These were isolated, subjected to tryptic digestion, and two of them were identified as ovomucoid and chicken riboflavin binding-protein following database matching of the peptide masses obtained by MALDI. The N-linked glycans were released from the glycoproteins and their structures were examined by MALDI-MS in combination with exoglycosidase digestion. Ovalbumin was found to be glycosylated mainly with high-mannose and hybrid structures, consistent with profiles obtained on the intact glycoprotein by electrospray. The other glycoproteins contained mainly larger, complex glycans with up to five antennae, many of which had earlier been associated with ovalbumin. (J Am Soc Mass Spectrom 2000, 11, 564 -571)
It is now well established that hypogalactosylation of IgG is a molecular marker for rheumatoid a... more It is now well established that hypogalactosylation of IgG is a molecular marker for rheumatoid arthritis (RA). However, the mechanism for the alteration of the galactosylation status has not been resolved. We compared the galactosyltransferase activities of anti-CD19 selected peripheral B lymphocytes of healthy subjects and patients with RA using ovalbumin as the acceptor substrate. In addition, certain samples of lymphocytes were assayed after Epstein-Barr virus (EBV) transformation and, also, the ability of bovine milk galactosyltransferase to galactosylate IgG in vitro was examined. Our results indicate that there is a significant difference between the galactosyltransferase activities of rheumatoid and control peripheral B lymphocytes and that EBV transformation causes a variable increase (15-1225%) in galactosyltransferase activity, over that present in the peripheral B lymphocytes from which the transformed cells were derived. Also the ubiquitous "lactose synthetase" type galactosyltransferase (EC 2.4.1.38) will galactosylate normal native IgG at concentrations of 500 mU/ml in vitro. We conclude that there is no evidence from our study for an IgG specific galactosyltransferase and that galactosyltransferase is an enzyme that is aberrantly modulated in peripheral B lymphocytes and EBV transformed B lymphoblasts derived from patients with RA.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any fo... more All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.71.102-05/05/12,18:10:25) ... 192 Silicon Carbide and Related Materials 2000 ... 194 Silicon Carbide and Related Materials 2000 ... Silicon Carbide and Related Materials 2000 10.4028/www.scientific.net/MSF.353-356 ... Structural and Optical Properties of SiC Films Deposited on Si by DC Magnetron
Human monoclonal antibodies to the Rh D blood group antigen were produced by EBV-transformed B ce... more Human monoclonal antibodies to the Rh D blood group antigen were produced by EBV-transformed B cell lines grown in serum-free medium in low density (LD) static cultures or high density (HD) hollow fiber bioreactors. Glycosylation analysis of the purified IgG was determined by the binding of anti-GlcNAc monoclonal antibody (GN7) and by analysis of oligosaccharides released by hydrazinolysis. The LD MAbs had only trace levels of agalactosyl oligosaccharides (G0), the major species (> 70%) being digalactosyl structures (G2). The HD MAbs, by contrast, contained about 10% G0 and relatively high levels (over 50%) of monogalactosyl (G1) oligosaccharides. beta 1-4 galactosyltransferase activity in the LD cell lines was similar to that found previously for other EBV-transformed B cell lines. The predominant oligosaccharides of an IgG3 anti-D, BRAD-3, contained bisecting N-acetylglucosamine. In functional assays with Fc receptor (Fc gamma R) positive effector cells, the highly galactosylated LD form of BRAD-3 was more active than the HD form in monocyte (Fc gamma RI) and K cell (Fc gamma RIII) mediated lysis of erythrocytes in ADCC assays, although these preparations showed no difference in Fc gamma RI-mediated rosette formation with U937 cells. One MAb, JAC10, was over 10-fold less active than two other IgG1 MAbs, 2B6 and BRAD-5, at mediating lysis of erythrocytes by Fc gamma RIII+ K cells; differences in sialylation may have contributed to this heterogeneity.(ABSTRACT TRUNCATED AT 250 WORDS)
The IgE of sera from patients with a history of allergy to oranges (Citrus sinensis) bind a numbe... more The IgE of sera from patients with a history of allergy to oranges (Citrus sinensis) bind a number of proteins in orange extract, including Cit s 1, a germin-like protein. In the present study, we have analysed its immunological cross-reactivity and its molecular nature. Sera from many of the patients examined recognise a range of glycoproteins and neoglycoconjugates containing β1,2-xylose and core α1,3-fucose on their Nglycans. These reagents also inhibited the interaction of Cit s 1 with patients' sera, thus underlining the critical role of glycosylation in the recognition of this protein by patients' IgE and extending previous data showing that deglycosylated Cit s 1 does not possess IgE epitopes. In parallel, we examined the peptide sequence and glycan structure of Cit s 1 using mass spectrometric techniques. Indeed, we achieved complete sequence coverage of the mature protein as compared to the translation of an expressed sequence tag cDNA clone and demonstrated that the single N-glycosylation site of this protein carries oligosaccharides with xylose and fucose residues. Due to the presumed requirement for multivalency for in vivo allergenicity, our molecular data showing that Cit s 1 is monovalent as regards glycosylation and that the single N-glycan is the target of the IgE response to this protein, therefore, explain the immunological cross-reactive properties of Cit s 1 as well as its equivocal nature as a clinically-relevant allergen.
Mosquitoes are important vectors of parasitic and viral diseases with Anopheles gambiae transmitt... more Mosquitoes are important vectors of parasitic and viral diseases with Anopheles gambiae transmitting malaria and Aedes aegypti spreading yellow and Dengue fevers. Using two different approaches (solid-phase extraction and reversed-phase or hydrophilic interaction HPLC fractionation followed by MALDI-TOF MS or permethylation followed by NSI-MS), we examined the N-glycans of both A. gambiae and A. aegypti larvae and demonstrate the presence of a range of paucimannosidic glycans as well as bi- and tri-antennary glycans, some of which are modified with fucose or with sulphate or glucuronic acid residues; the latter anionic modifications were also found on N-glycans of larvae from another dipteran species (Drosophila melanogaster). The sulphate groups are attached primarily to core α-mannose residues (especially the α1,6-linked mannose), whereas the glucuronic acid residues are linked to non-reducing β1,3-galactose. Also, O-glycans were found to possess glucuronic acid and sulphate as we...
Molecular & cellular proteomics : MCP, Jan 22, 2015
The N-glycosylation of the model nematode Caenorhabiditis elegans has proven to be highly variabl... more The N-glycosylation of the model nematode Caenorhabiditis elegans has proven to be highly variable and rather complex; it is an example to contradict the existing impression that 'simple' organisms possess also a rather simple glycomic capacity. In previous studies in a number of laboratories, N-glycans with up to four fucose residues have been detected. However, although the linkage of three fucose residues to the N,N'-diacetylchitobiosyl core has been proven by structural and enzymatic analyses, the nature of the fourth fucose has remained uncertain. By constructing a triple mutant with deletions in the three genes responsible for core fucosylation (fut-1, fut-6 and fut-8), we have produced a nematode strain lacking products of these enzymes, but still retaining maximally one fucose residue on its N-glycans. Using mass spectrometry and HPLC in conjunction with chemical and enzymatic treatments as well as NMR, we examined a set of α-mannosidase-resistant N-glycans. With...
The locations of cytochrome c peroxidase and catalase activities in the two Gram-negative bacteri... more The locations of cytochrome c peroxidase and catalase activities in the two Gram-negative bacteria Pseudomonas stutzeri (N.C.I.B. 9721) and Paracoccus denitrificans (N.C.I.B. 8944) were investigated by the production of spheroplasts. In both species the cytochrome c peroxidase was predominantly periplasmic: 92% of total activity in Ps. stutzeri and 98% of nonmembrane-bound activity in Pa. denitrificans were found in this cellular compartment. In contrast, the catalase was mostly in the cytoplasmic fraction. Purification of the Pa. denitrificans cytochrome c peroxidase showed it to be the haem c-containing polypeptide of Mr 42,000 that has already been described by Bosma, Braster, Stouthamer & Van Versefeld [(1987) Eur. J. Biochem. 165, 665-670] but was not identified by them as a peroxidase. The visible-absorption spectra of the enzyme closely resemble those of cytochrome c peroxidase from Pseudomonas aeruginosa but the donor specificity is different, with the Pa. denitrificans enzy...
Baculovirus-mediated expression in insect cells has become well-established for the production of... more Baculovirus-mediated expression in insect cells has become well-established for the production of recombinant glycoproteins. Its frequent use arises from the relative ease and speed with which a heterologous protein can be expressed on the laboratory scale and the high chance of obtaining a biologically active protein. In addition to Spodoptera frugiperda Sf9 cells, which are probably the most widely used insect cell line, other mainly lepidopteran cell lines are exploited for protein expression. Recombinant baculovirus is the usual vector for the expression of foreign genes but stable transfection of - especially dipteran - insect cells presents an interesting alternative. Insect cells can be grown on serum free media which is an advantage in terms of costs as well as of biosafety. For large scale culture, conditions have been developed which meet the special requirements of insect cells. With regard to protein folding and post-translational processing, insect cells are second only...
Dolichol is utilized in vivo as an unusually large anchor on which the precursor for N-linked oli... more Dolichol is utilized in vivo as an unusually large anchor on which the precursor for N-linked oligosaccharides is assembled by a series of glycosyltransferases. The role of dolichol in enzyme substrate recognition is investigated. Thus the biosynthetic intermediate NN'-diacetylchitobiose was chemically linked to either dolichol or the much shorter fully saturated tetraisoprenoid phytanol. Both lipids were used as substrates by a recombinant, soluble beta-1,4-mannosyltransferase. beta-[3H]Mannosylated lipids from this reaction were then used as substrates for the subsequent mannosyltransferases from yeast or rat liver microsomes. It was found that both the dolichyl- and phytanyl-linked substrates were easily mannosylated to form Man5GlcNAc2, with some further mannosylation to Man7GlcNAc2 and Man9GlcNAc2 at low concentrations of lipid-linked substrate. It is concluded that dolichol is not necessary in vitro as part of the substrate for the mannosyltransferases in the biosynthetic ...
Carbohydrates are known as sources of immunological cross-reactivity of allergenic significance. ... more Carbohydrates are known as sources of immunological cross-reactivity of allergenic significance. In celery and in cypress pollen, the major allergens Api g 5 and Cup a 1 are recognised by antisera raised against anti-horseradish peroxidase and by patients' IgE which apparently bind carbohydrate epitopes; mass spectrometric analysis of the tryptic peptides and of their N-glycans showed the presence of oligosaccharides carrying both xylose and core alpha1,3-fucose residues. Core alpha1,3-fucose residues are also a feature of invertebrates: genetic and biochemical studies on the fruitfly Drosophila melanogaster, the parasitic trematode Schistosoma mansoni and the nematode worm Caenorhabditis elegans indicate that these organisms possess core alpha1,3-fucosyltransferases. Various experiments have shown that fucosyltransferases from both fly and worm are responsible in vivo and in vitro for the synthesis of N-glycans which cross-react with anti-horseradish peroxidase; thus, we can co...
Pristionchus pacificus is a free-living nematode increasingly used as an organism for comparison ... more Pristionchus pacificus is a free-living nematode increasingly used as an organism for comparison to the more familiar model Caenorhabditis elegans. In this study, we examined the N-glycans of this organism isolated after serial release with peptide:N-glycosidases F and A; after fluorescent labelling with 2-aminopyridine, chromatographic fractionation by three types of reversed-phase HPLC (with either classical C18, fused core C18 or alkylamide bonded phases) followed by mass spectrometric analyses revealed key features of its N-glycome. In addition to paucimannosidic and oligomannosidic glycans typical of invertebrates, N-glycans with two core fucose residues were detected. Furthermore, a range of glycans carrying up to three phosphorylcholine residues was observed whereas, unlike C. elegans, no tetrafucosylated N-glycans were detected. Structures with three fucose residues, unusual methylation of core α1,3-fucose or with galactosylated fucose motifs were found in low amounts; these...
N-glycans from the nematode Haemonchus contortus (barber pole worm), a parasite of sheep and catt... more N-glycans from the nematode Haemonchus contortus (barber pole worm), a parasite of sheep and cattle, were the first to be described to possess up to three fucose residues associated with the N,N'-diacetylchitobiosyl core, two being on the reducing-terminal proximal GlcNAc and one on the distal core GlcNAc residue. The assumption was that truncated glycans from this organism with three hexose residues have the composition Man3GlcNAc2Fuc1-3. In this study we have performed HPLC and MALDI-TOF MS/MS in combination with selected digestions of N-glycans from Haemonchus. A dominant trifucosylated Hex3HexNAc2Fuc3 glycan was modified not only with α1,6-fucose, but also with a proximal core α1,3-fucose and a galactosylated distal α1,3-fucose; thereby, only two of the hexose residues were mannose. Other N-glycans displayed galactosylation of the core α1,6-fucose, antennal fucosylation or modification with phosphorylcholine. Thus, the N-glycans of Haemonchus contain a number of potentially ...
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