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Cudic M, Burstein GD. Preparation of glycosylated amino acids suitable for Fmoc solid-phase assembly. Methods Mol Biol 2008; 494:187-208. [PMID: 18726575 DOI: 10.1007/978-1-59745-419-3_11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Many biological interactions and functions are mediated by glycans, consequently leading to the emerging importance of carbohydrate and glycoconjugate chemistry in the design of novel drug therapeutics. Despite the challenges that carbohydrate moieties bring into the synthesis of glycopeptides and glycoproteins, considerable progress has been made during recent decades. Glycopeptides carrying many simple glycans have been chemically synthesized, enzymatic approaches have been utilized to introduce more complex glycans, and most recently native chemical ligation has enabled synthesis of glycoproteins from well-designed peptide and glycopeptide building blocks. Currently, general synthetic methodology for glycopeptides relies on preformed glycosylated amino acids for the stepwise solid-phase peptide synthesis. The formation of glycosidic bonds is of fundamental importance in the assembly of glycopeptides. As such, every glycosylation has to be regarded as a unique problem, demanding considerable systematic research. In this chapter we will summarize the most common chemical methods for the stereoselective synthesis of N- and O-glycosylated amino acids. The particular emphasis will be given to the preparation of building blocks for use in solid-phase glycopeptide synthesis based on the 9-fluorenylmethoxycarbonyl (Fmoc) protective group strategy.
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Affiliation(s)
- Mare Cudic
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL, USA
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252
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Gu Y, Lewis DF, Wang Y. Placental productions and expressions of soluble endoglin, soluble fms-like tyrosine kinase receptor-1, and placental growth factor in normal and preeclamptic pregnancies. J Clin Endocrinol Metab 2008; 93:260-6. [PMID: 17956952 PMCID: PMC2190747 DOI: 10.1210/jc.2007-1550] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CONTEXT Increased production of antiangiogenic factors soluble endoglin (sEng) and soluble fms-like tyrosine kinase receptor-1 (sFlt-1) by the placenta contributes to the pathophysiology in preeclampsia (PE). OBJECTIVE Our objective was to determine the differences in endoglin (Eng), fms-like tyrosine kinase receptor-1 (Flt-1), and placental growth factor (PlGF) expressions between normal and PE placentas and sEng, sFlt-1, and PlGF production by trophoblast cells (TC) cultured under lowered oxygen conditions. METHODS TCs isolated from normal and PE placentas were cultured under regular (5% CO2/air) and lowered (2% O2/5% CO2/93% N2) oxygen conditions. sEng, sFlt-1, and PlGF productions were determined by ELISA. Protein expressions for Eng, Flt-1, and PlGF in the placental tissues were accessed by immunohistochemical staining and Western blot analysis. Deglycosylated Eng, Flt-1, and PlGF protein expressions in placental tissues were also examined. RESULTS PE TCs produced significantly more sEng, sFlt-1, and PlGF compared with those from normal TCs (P < 0.05). Under lowered oxygen conditions, PE TCs, but not normal TCs, released more sEng and sFlt-1. In contrast, both normal and PE TCs released less PlGF (P < 0.05). Enhanced expressions of Eng and Flt-1, as well as glycosylated Eng and Flt-1, were observed in PE placentas. Immunoblot also revealed that TCs released glycosylated sFlt-1, but not sEng, in culture. CONCLUSIONS PE TCs produce more sEng, sFlt-1, and PlGF than normal TCs. Lowered oxygen conditions promote sEng and sFlt-1, but reduce PlGF, productions by PE TCs. More glycosylated sEng and sFlt-1 are present in PE placentas. Trophoblasts release glycosylated sFlt-1, but unglycosylated sEng, in culture.
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Affiliation(s)
- Yang Gu
- Department of Obstetrics and Gynecology, Louisiana State University Health Sciences Center-Shreveport, PO Box 33932, Shreveport, Louisiana 71130, USA
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253
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Atwood JA, Cheng L, Alvarez-Manilla G, Warren NL, York WS, Orlando R. Quantitation by isobaric labeling: applications to glycomics. J Proteome Res 2007; 7:367-74. [PMID: 18047270 DOI: 10.1021/pr070476i] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The study of glycosylation patterns (glycomics) in biological samples is an emerging field that can provide key insights into cell development and pathology. A current challenge in the field of glycomics is to determine how to quantify changes in glycan expression between different cells, tissues, or biological fluids. Here we describe a novel strategy, quantitation by isobaric labeling (QUIBL), to facilitate comparative glycomics. Permethylation of a glycan with (13)CH 3I or (12)CH 2DI generates a pair of isobaric derivatives, which have the same nominal mass. However, each methylation site introduces a mass difference of 0.002922 Da. As glycans have multiple methylation sites, the total mass difference for the isobaric pair allows separation and quantitation at a resolution of approximately 30000 m/Delta m. N-Linked oligosaccharides from a standard glycoprotein and human serum were used to demonstrate that QUIBL facilitates relative quantitation over a linear dynamic range of 2 orders of magnitude and permits the relative quantitation of isomeric glycans. We applied QUIBL to quantitate glycomic changes associated with the differentiation of murine embryonic stem cells to embryoid bodies.
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Affiliation(s)
- James A Atwood
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602-4712, USA
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254
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Scheibner M, Hülsdau B, Zelena K, Nimtz M, de Boer L, Berger RG, Zorn H. Novel peroxidases of Marasmius scorodonius degrade beta-carotene. Appl Microbiol Biotechnol 2007; 77:1241-50. [PMID: 18038130 DOI: 10.1007/s00253-007-1261-9] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Revised: 10/22/2007] [Accepted: 10/23/2007] [Indexed: 10/22/2022]
Abstract
Two extracellular enzymes (MsP1 and MsP2) capable of efficient beta-carotene degradation were purified from culture supernatants of the basidiomycete Marasmius scorodonius (garlic mushroom). Under native conditions, the enzymes exhibited molecular masses of approximately 150 and approximately 120 kDa, respectively. SDS-PAGE and mass spectrometric data suggested a composition of two identical subunits for both enzymes. Biochemical characterisation of the purified proteins showed isoelectric points of 3.7 and 3.5, and the presence of heme groups in the active enzymes. Partial amino acid sequences were derived from N-terminal Edman degradation and from mass spectrometric ab initio sequencing of internal peptides. cDNAs of 1,604 to 1,923 bp, containing open reading frames (ORF) of 508 to 513 amino acids, respectively, were cloned from a cDNA library of M. scorodonius. These data suggest glycosylation degrees of approximately 23% for MsP1 and 8% for MsP2. Databank homology searches revealed sequence homologies of MsP1 and MsP2 to unusual peroxidases of the fungi Thanatephorus cucumeris (DyP) and Termitomyces albuminosus (TAP).
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Affiliation(s)
- Manuela Scheibner
- Zentrum Angewandte Chemie, Institut für Lebensmittelchemie der Universität Hannover, Wunstorfer Strasse 14, 30453, Hannover, Germany
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255
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Doddi VR, Vankar YD. Synthesis of Pyrrolidine-Based Imino Sugars as Glycosidase Inhibitors. European J Org Chem 2007. [DOI: 10.1002/ejoc.200700719] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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256
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Costello CE, Contado-Miller JM, Cipollo JF. A glycomics platform for the analysis of permethylated oligosaccharide alditols. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:1799-812. [PMID: 17719235 PMCID: PMC4383468 DOI: 10.1016/j.jasms.2007.07.016] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 07/03/2007] [Accepted: 07/06/2007] [Indexed: 05/09/2023]
Abstract
This communication reports the development of an LC/MS platform for the analysis of permethylated oligosaccharide alditols that, for the first time, demonstrates routine online oligosaccharide isomer separation of these compounds before introduction into the mass spectrometer. The method leverages a high-resolution liquid chromatography system with the superior fragmentation pattern characteristics of permethylated oligosaccharide alditols that are dissociated under low-energy collision conditions using quadrupole orthogonal time-of-flight (QoTOF) instrumentation and up to pseudo MS(3) mass spectrometry. Glycoforms, including isomers, are readily identified and their structures assigned. The isomer-specific spectra include highly informative cross-ring and elimination fragments, branch position specific signatures, and glycosidic bond fragments, thus facilitating linkage, branch, and sequence assignment. The method is sensitive and can be applied using as little as 40 fmol of derivatized oligosaccharide. Because permethylation renders oligosaccharides nearly chemically equivalent in the mass spectrometer, the method is semiquantitative and, in this regard, is comparable to methods reported using high field NMR and capillary electrophoresis. In this postgenomic age, the importance of glycosylation in biological processes has become clear. The nature of many of the important questions in glycomics is such that sample material is often extremely limited, thus necessitating the development of highly sensitive methods for rigorous structural assignment of the oligosaccharides in complex mixtures. The glycomics platform presented here fulfills these criteria and should lead to more facile glycomics analyses.
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Affiliation(s)
- Catherine E Costello
- Mass Spectrometry Resource, Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
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257
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Rizvi S, Banu N. Physicochemical properties and oxidative inactivation of soluble lectin from water buffalo (Bubalus bubalis) brain. Neurochem Res 2007; 33:468-76. [PMID: 17763948 DOI: 10.1007/s11064-007-9456-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Accepted: 07/23/2007] [Indexed: 11/29/2022]
Abstract
Lectins are carbohydrate-binding proteins present in a wide variety of plants and animals, which serve various important physiological functions. A soluble beta-galactoside binding lectin has been isolated and purified to homogeneity from buffalo brain using ammonium sulphate precipitation (40-70%) and gel permeation chromatography on Sephadex G50-80 column. The molecular weight of buffalo brain lectin (BBL) as determined by SDS-PAGE under reducing and non-reducing conditions was 14.2 kDa, however, with gel filtration it was 28.5 kDa, revealing the dimeric form of protein. The neutral sugar content of the soluble lectin was estimated to be 3.3%. The BBL showed highest affinity for lactose and other sugar moieties in glycosidic form, suggesting it to be a beta-galactoside binding lectin. The association constant for lactose binding as evidenced by Scatchard analysis was 6.6 x 10(3) M(-1) showing two carbohydrate binding sites per lectin molecule. A total inhibition of lectin activity was observed by denaturants like guanidine HCl, thiourea and urea at 6 M concentration. The treatment of BBL with oxidizing agent destroyed its agglutination activity, abolished its fluorescence, and shifted its UV absorption maxima from 282 to 250 nm. The effect of H2O2 was greatly prevented by lactose indicating that BBL is more stable in the presence of its specific ligand. The purified lectin was investigated for its brain cell aggregation properties by testing its ability to agglutinate cells isolated from buffalo and goat brains. Rate of aggregation of buffalo brain cells by purified protein was more than the goat brain cells. The data from above study suggests that the isolated lectin may belong to the galectin-1 family but is glycosylated unlike those purified till date.
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Affiliation(s)
- Sabika Rizvi
- Department of Biochemistry, Faculty of Life Sciences, A.M. University, Aligarh, UP 202002, India
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258
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Norgren AS, Geitmann M, Danielson UH, Arvidsson PI. Biomolecular recognition of glycosylated beta(3)-peptides by GalNAc specific lectins. J Mol Recognit 2007; 20:132-8. [PMID: 17410519 DOI: 10.1002/jmr.821] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The molecular recognition of a novel kind of hybrid conjugates, composed of artificial biomimetic beta-peptide oligomers with an O-linked natural N-acetyl-galactosamine (the Tn-antigen) residue, by four different GalNAc specific lectins was investigated using surface plasmon biosensor technology. The influence of the peptide and the glycosyl moiety on the recognition was studied using two glycosylated beta(3)-heptapeptides, a glycosylated alpha-heptapeptide, two beta-amino acid containing dipeptides, and monomeric alphaGalNAc-O-Thr. Although all four lectins displayed a decreased affinity for the carbohydrate residue when attached to a peptide, as compared to the monomeric Tn-antigen, the peptide part was found to have distinct effects on the binding kinetics-indicating that varying degrees of protein-peptide interactions occurred in the recognition process. Likewise, the lectins did not discriminate between beta(3)-peptides and the alpha-peptide, but the beta-linkage of the galactose had a detrimental effect for at least two of the lectins.
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Affiliation(s)
- Anna S Norgren
- Department of Biochemistry and Organic Chemistry, Uppsala University, Sweden
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259
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Abstract
This overview presents curcumin as a significant chemosensitizer in cancer chemotherapy. Although the review focuses on curcumin and its analogues on multidrug resistance (MDR) reversal, the relevance of curcumin as a nuclear factor (NF)-KB blocker and sensitizer of many chemoresistant cancer cell lines to chemotherapeutic agents will also be discussed. One of the major mechanisms of MDR is the enhanced ability of tumor cells to actively efflux drugs, leading to a decrease in cellular drug accumulation below toxic levels. Active drug efflux is mediated by several members of the ATP-binding cassette (ABC) superfamily of membrane transporters, which have now been subdivided into seven families designated A through G. Among these ABC families, the classical MDR is attributed to the elevated expression of ABCB1 (Pgp), ABCC1 (MRP1), and ABCG2 (MXR). The clinical importance of Pgp, MRP1, and MXR for MDR and cancer treatment has led to the investigation of the inhibiting properties of several compounds on these transporters. At present, due in part to the disappointing results associated with the many side effects of synthetic modulators that have been used in clinical trials, current research efforts are directed toward the identification of novel compounds, with attention to dietary natural products. The advantage is that they exhibit little or virtually no side effects and do not further increase the patient's medication burden.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Antineoplastic Agents/metabolism
- Antineoplastic Agents, Phytogenic/metabolism
- Apoptosis/drug effects
- Curcumin/analogs & derivatives
- Curcumin/chemistry
- Curcumin/pharmacology
- Drug Resistance, Multiple/drug effects
- Drug Resistance, Neoplasm/genetics
- Forecasting
- Gene Expression Regulation, Neoplastic
- Humans
- Mitoxantrone/metabolism
- Neoplasms/drug therapy
- Neoplasms/genetics
- Neoplasms/metabolism
- Neoplasms, Experimental/drug therapy
- Neoplasms, Experimental/genetics
- Neoplasms, Experimental/metabolism
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Affiliation(s)
- Pornngarm Limtrakul
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Thailand.
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260
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Skropeta D, Settasatian C, McMahon MR, Shearston K, Caiazza D, McGrath KC, Jin W, Rader DJ, Barter PJ, Rye KA. N-Glycosylation regulates endothelial lipase-mediated phospholipid hydrolysis in apoE- and apoA-I-containing high density lipoproteins. J Lipid Res 2007; 48:2047-57. [PMID: 17545692 DOI: 10.1194/jlr.m700248-jlr200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endothelial lipase (EL) is a member of the triglyceride lipase gene family with high phospholipase and low triacylglycerol lipase activities and a distinct preference for hydrolyzing phospholipids in HDL. EL has five potential N-glycosylation sites, four of which are glycosylated. The aim of this study was to determine how glycosylation affects the phospholipase activity of EL in physiologically relevant substrates. Site-directed mutants of EL were generated by replacing asparagine (N) 62, 118, 375, and 473 with alanine (A). These glycan-deficient mutants were used to investigate the kinetics of phospholipid hydrolysis in fully characterized preparations of spherical reconstituted high density lipoprotein (rHDL) containing apolipoprotein E2 (apoE2) [(E2)rHDL], apoE3 [(E3)rHDL], apoE4 [(E4)rHDL], or apoA-I [(A-I)rHDL] as the sole apolipoprotein. Wild-type EL hydrolyzed the phospholipids in (A-I)rHDL, (E2)rHDL, (E3)rHDL, and (E4)rHDL to similar extents. The phospholipase activities of EL N118A, EL N375A, and EL N473A were significantly diminished relative to that of wild-type EL, with the greatest reduction being apparent for (E3)rHDL. The phospholipase activity of EL N62A was increased up to 6-fold relative to that of wild-type EL, with the greatest enhancement of activity being observed for (E2)rHDL. These data show that individual N-linked glycans have unique and important effects on the phospholipase activity and substrate specificity of EL.
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Affiliation(s)
- Danielle Skropeta
- Lipid Research Group, Heart Research Institute, Camperdown, New South Wales 2050, Australia
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261
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Arjona O, Gómez AM, López JC, Plumet J. Synthesis and Conformational and Biological Aspects of Carbasugars. Chem Rev 2007; 107:1919-2036. [PMID: 17488060 DOI: 10.1021/cr0203701] [Citation(s) in RCA: 277] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Odón Arjona
- Departamento de Química Orgánica, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
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262
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N-Glycosylation sites of plant purple acid phosphatases important for protein expression and secretion in insect cells. Arch Biochem Biophys 2007; 461:247-54. [DOI: 10.1016/j.abb.2007.02.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 02/05/2007] [Accepted: 02/07/2007] [Indexed: 11/20/2022]
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263
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Zheng P, Vassena R, Latham KE. Effects of in vitro oocyte maturation and embryo culture on the expression of glucose transporters, glucose metabolism and insulin signaling genes in rhesus monkey oocytes and preimplantation embryos. Mol Hum Reprod 2007; 13:361-71. [PMID: 17416905 DOI: 10.1093/molehr/gam014] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glucose plays a fundamental role during oogenesis and embryogenesis, satisfying the metabolic demands of oocytes and embryos, providing for stored energy reserves in the form of glycogen and supporting nucleotide biosynthesis via the pentose phosphate pathway. Glucose also contributes to the production of amino acids, glycosylated proteins and extracellular components. A detailed understanding of the molecular mechanisms that mediate and regulate glucose uptake and metabolism at different stages of oogenesis and preimplantation embryogenesis could greatly benefit the development of improved methods for in vitro oocyte maturation and in vitro embryo production. Although these processes have been examined in a variety of rodent and agricultural species, detailed information has not yet been described for non-human primates. In this study, we examined the expression of the genes encoding glucose transporters, glucose metabolism enzymes and potential regulators of glucose metabolism in rhesus monkey oocytes and embryos. The data reveal stage-specific regulation of expression of specific types of glucose transporters, stage-specific changes in expression of genes related to different pathways of glucose metabolism and temporal changes in the expression of mRNAs related to insulin signaling. Additionally, the data reveal significant differences in expression of some of these genes in cultured embryos as compared with flushed embryos and between oocytes and embryos obtained following different hormonal stimulation and oocyte maturation protocols.
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Affiliation(s)
- Ping Zheng
- The Fels Institute for Cancer Research and Molecular Biology, Temple University Medical School, 3307 North Broad Street, Philadelphia, PA 19140, USA
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264
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García PA, de Oliveira AB, Batista R. Occurrence, biological activities and synthesis of kaurane diterpenes and their glycosides. Molecules 2007; 12:455-83. [PMID: 17851404 PMCID: PMC6149336 DOI: 10.3390/12030455] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2007] [Revised: 03/12/2007] [Accepted: 03/12/2007] [Indexed: 12/20/2022] Open
Abstract
This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed.
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Affiliation(s)
- Pablo Anselmo García
- Departamento de Química Farmacéutica, Facultad de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain; E-mail:
| | - Alaíde Braga de Oliveira
- Departamento de Produtos Farmacêuticos, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte – MG, Brazil; E-mail:
| | - Ronan Batista
- Departamento de Estudos Básicos e Instrumentais, Universidade Estadual do Sudoeste da Bahia, BR 415, Km 03, s/nº, 45.700-000 Itapetinga – BA, Brazil
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265
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Fahmi NE, Dedkova L, Wang B, Golovine S, Hecht SM. Site-Specific Incorporation of Glycosylated Serine and Tyrosine Derivatives into Proteins. J Am Chem Soc 2007; 129:3586-97. [PMID: 17338522 DOI: 10.1021/ja067466n] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glycosylation of proteins can have a dramatic effect on their physical, chemical, and biological properties. Analogues of dihydrofolate reductase and firefly luciferase containing glycosylated amino acids at single, predetermined sites have been elaborated. Misacylated suppressor tRNAs activated with glycosylated serine and tyrosine derivatives were used for suppression of the nonsense codons in a cell-free protein biosynthesizing system, thereby permitting the preparation of the desired glycosylated proteins. In this fashion, it was possible to obtain proteins containing both mono- and diglycosylated amino acids, including glycosylated serine and tyrosine moieties. For the modified firefly luciferases, the effect of these substitutions on the wavelength of the light emitted by firefly luciferase was investigated. The maximum wavelength for mutants containing peracetylated glycosylated serine derivatives at position 284 showed a red shift in the emission spectra. For mutants containing glycosylated tyrosines, the red shift was observed only when the carbohydrate moiety was fully deacetylated.
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Affiliation(s)
- Nour Eddine Fahmi
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
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266
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Gaisberger R, Weis R, Luiten R, Skranc W, Wubbolts M, Griengl H, Glieder A. Counteracting expression deficiencies by anticipating posttranslational modification of PaHNL5-L1Q-A111G by genetic engineering. J Biotechnol 2007; 129:30-8. [PMID: 17234294 DOI: 10.1016/j.jbiotec.2006.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 08/11/2006] [Accepted: 10/09/2006] [Indexed: 10/23/2022]
Abstract
(R)-2-chloromandelic acid represents a key pharmaceutical intermediate. Its production on large scale was hampered by low turnover rates and moderate enantiomeric excess (ee) using enzyme as well as metal catalysts. The cloning and heterologous overexpression of an (R)-hydroxynitrile lyase from Prunus amygdalus opened a way to large-scale production of this compound. Especially the rationally designed mutation of alanine to glycine at amino acid position 111 of the mature protein tremendously raised the yield for enantioselective conversion of 2-chlorobenzaldehyde to (R)-2-chloromandelonitrile, which can be hydrolysed to the corresponding alpha hydroxy acid. However, expression of this mutein was less efficient than for the unmodified enzyme. Subsequent LC/MS/MS-analysis of the protein sequence revealed that mutation A111G triggered the posttranslational deamidation of the neighbouring residue asparagine (N110) to aspartic acid. This finding on the one hand could explain the decreased secretion efficiency of the mutant as compared to the wildtype enzyme, but on the other hand raised the question which of the two residues was truly accountable for the enhanced conversion. The muteins N110D, A111G and N110DA111G were constructed and compared in terms of protein productivity and performance in chemical syntheses. The expression level of the double mutein was augmented significantly and the enantioselectivity remained high. Reduced protein expression of mutein PaHNL5-L1Q-A111G was remedied by mutational anticipation of posttranslational deamidation.
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Affiliation(s)
- Richard Gaisberger
- Research Centre Applied Biocatalysis, Institute of Organic Chemistry, Graz University of Technology, Stremayrgasse 16, A-8010 Graz, Austria
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267
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Weis R, Gaisberger R, Gruber K, Glieder A. Serine scanning—A tool to prove the consequences of N-glycosylation of proteins. J Biotechnol 2007; 129:50-61. [PMID: 17224199 DOI: 10.1016/j.jbiotec.2006.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 08/02/2006] [Accepted: 08/15/2006] [Indexed: 11/20/2022]
Abstract
N-Glycosylation of proteins is a common posttranslational modification in eukaryotes. Often this results in enhanced protein stability through protection by the attached sugar moieties. Due to its 13 potential N-glycosylation motifs (N-X-T/S), recombinant hydroxynitrile lyase isoenzyme 5 from almonds (PaHNL5) is secreted by the heterologous host Pichia pastoris in a massively glycosylated form, and it shows extraordinary stability at low pH. The importance of N-glycosylation in general, and individual glycosylation sites in particular for stability at low pH were investigated. To identify especially important glycosylation sites asparagine from all N-X-S/T-motifs was replaced by serine. Thus, critical sites, which contributed to overall enzyme activity and/or stability, were identified individually. One glycosylation site revealed to be essential for stability at low pH. After enzymatic deglycosylation, leaving only one acetylglucosamine attached to asparagines, PaHNL5 retained most of its stability at low pH. Protonation effects in the active site as well as higher-order aggregational events upon incubation in low pH were excluded. This study provides evidence for the interconnection of N-glycosylation and stability at low pH for PaHNL5. Moreover, serine scanning was proven to be applicable for quick identification of critical glycosylation sites.
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Affiliation(s)
- Roland Weis
- Research Centre Applied Biocatalysis, Graz, Austria
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Fatima A, Husain Q. A role of glycosyl moieties in the stabilization of bitter gourd (Momordica charantia) peroxidase. Int J Biol Macromol 2007; 41:56-63. [PMID: 17320168 DOI: 10.1016/j.ijbiomac.2006.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 12/21/2006] [Accepted: 12/22/2006] [Indexed: 10/23/2022]
Abstract
The possible role of carbohydrate moieties in the stabilization of proteins has been investigated by using bitter gourd peroxidase as a model system. A comparative study of glycosylated and non-glycosylated isoenzymes of bitter gourd peroxidase was performed at various temperatures, pH, water-miscible organic solvents, detergents and chaotropic agent like urea. The pH-optima and temperature-optima of both glycosylated and non-glycosylated isoforms of bitter gourd peroxidase remained unchanged. The probes employed were changes in the enzyme activity and fluorescence. The glycosylated form of peroxidase retained greater fraction of enzyme activity against the exposure caused by various physical and chemical denaturants. The unfolding of both forms of enzyme in the presence of high urea concentrations, studied by fluorescence, indicated greater perturbations in the conformation of non-glycosylated preparation. The different properties examined thus indicated that glycosylation plays an important role in the stabilization of native conformation of proteins against the inactivation caused by various types of denaturants.
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Affiliation(s)
- Aiman Fatima
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202 002, UP, India
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270
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Shin DH, Webb B, Nakao M, Smith SL. Molecular cloning, structural analysis and expression of complement component Bf/C2 genes in the nurse shark, Ginglymostoma cirratum. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2007; 31:1168-82. [PMID: 17482263 DOI: 10.1016/j.dci.2007.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Revised: 02/05/2007] [Accepted: 03/04/2007] [Indexed: 05/15/2023]
Abstract
Factor B and C2 are serine proteases that provide the catalytic subunits of C3 and C5 convertases of the alternative (AP) and classical (CP) complement pathways. Two Bf/C2 cDNAs, GcBf/C2-1 and -2 (previously referred to as nsBf/C2-A and nsBf/C2-B), were isolated from the nurse shark, Ginglymostoma cirratum. GcBf/C2-1 and -2 are 3364 and 3082bp in length and encode a leader peptide, three CCPs, one VWFA, the serine protease domain and have a putative factor D/C1s/MASP cleavage site. Southern blots show that there might be up to two Bf/C2-like genes for each of the two GcBf/C2 isoforms. GcBf/C2-1 and -2 are constitutively expressed, albeit at different levels, in all nine tissues examined. Expression in erythrocytes is a novel finding. Structural analysis has revealed that the localization of glycosylation sites in the SP domain of both putative proteins indicates that the molecular organization of the shark molecules is more like C2 than factor B. Phylogenetic analysis indicates that GcBf/C2-1 and -2 and TrscBf of Triakis scyllia (another shark species) originated from a common ancestor and share a remote ancestor with Bf and C2 of mammals and bony fish.
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Affiliation(s)
- Dong-Ho Shin
- Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199, USA
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271
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Norgren AS, Norberg T, Arvidsson PI. Glycosylated foldamers: synthesis of carbohydrate-modified β3hSer and incorporation into β-peptides. J Pept Sci 2007; 13:717-27. [PMID: 17890640 DOI: 10.1002/psc.832] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Fmoc-protected beta(3)hserine (beta(3)hSer) was prepared and O-linked to suitably protected N-acetylgalactosamine (GalNAc) and N-acetylglucosamine (GlcNAc) derivatives. Glycosylation of beta(3)hSer was made by two independent routes: either by direct glycosyl linkage to the beta(3)hSer, or linkage to natural L-Ser and then utilizing the carbohydrate moiety as a protecting group in an Arndt-Eistert homologation. Both procedures gave the novel glycosylated beta(3)-amino acids Fmoc-beta(3)hSer(alpha-D-GalNAc(Ac)(3))-OH (1a), its beta-anomer (1b), and Fmoc-beta(3)hSer(beta-D-GlcNAc(Ac)(3))-OH (2), which were utilized in the solid-phase peptide synthesis of four glycosylated dipeptides (3a-d) and two heptapeptides (4a-b). The preparation of beta-amino acids bearing common post-translational modifiers represents an important step towards functionalized foldamers with broad applications in biomedical research.
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Affiliation(s)
- Anna S Norgren
- Department of Biochemistry & Organic Chemistry, Uppsala University, S-75123 Uppsala, Sweden
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272
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Harrison RL, Jarvis DL. Protein N-glycosylation in the baculovirus-insect cell expression system and engineering of insect cells to produce "mammalianized" recombinant glycoproteins. Adv Virus Res 2006; 68:159-91. [PMID: 16997012 DOI: 10.1016/s0065-3527(06)68005-6] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Baculovirus expression vectors are frequently used to express glycoproteins, a subclass of proteins that includes many products with therapeutic value. The insect cells that serve as hosts for baculovirus vector infection are capable of transferring oligosaccharide side chains (glycans) to the same sites in recombinant proteins as those that are used for native protein N-glycosylation in mammalian cells. However, while mammalian cells produce compositionally more complex N-glycans containing terminal sialic acids, insect cells mostly produce simpler N-glycans with terminal mannose residues. This structural difference between insect and mammalian N-glycans compromises the in vivo bioactivity of glycoproteins and can potentially induce allergenic reactions in humans. These features obviously compromise the biomedical value of recombinant glycoproteins produced in the baculovirus expression vector system. Thus, much effort has been expended to characterize the potential and limits of N-glycosylation in insect cell systems. Discoveries from this research have led to the engineering of insect N-glycosylation pathways for assembly of mammalian-style glycans on baculovirus-expressed glycoproteins. This chapter summarizes our knowledge of insect N-glycosylation pathways and describes efforts to engineer baculovirus vectors and insect cell lines to overcome the limits of insect cell glycosylation. In addition, we consider other possible strategies for improving glycosylation in insect cells.
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Affiliation(s)
- Robert L Harrison
- Insect Biocontrol Laboratory, USDA Agricultural Research Service, Plant Sciences Institute, 10300 Baltimore Avenue, Beltsville, Maryland 20705, USA
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273
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Lehle L, Strahl S, Tanner W. Proteinglycosylierung, konserviert von der Bäckerhefe bis zum Menschen: Ein Modellorganismus hilft bei der Aufklärung menschlicher Erbkrankheiten. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200601645] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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274
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Lehle L, Strahl S, Tanner W. Protein Glycosylation, Conserved from Yeast to Man: A Model Organism Helps Elucidate Congenital Human Diseases. Angew Chem Int Ed Engl 2006; 45:6802-18. [PMID: 17024709 DOI: 10.1002/anie.200601645] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Proteins can be modified by a large variety of covalently linked saccharides. The present review concentrates on two types, protein N-glycosylation and protein O-mannosylation, which, with only a few exceptions, are evolutionary conserved from yeast to man. They are also distinguished by some special features: The corresponding glycosylation processes start in the endoplasmatic reticulum, are continued in the Golgi apparatus, and require dolichol-activated precursors for the initial biosynthetic steps. With respect to the molecular biology of both types of protein glycosylation, the pathways and the genetic background of the reactions have most successfully been studied with the genetically easy-to-handle baker's yeast, Saccharomyces cerevisae. Many of the severe developmental disturbances in children are related to protein glycosylation, for example, the CDG syndrome (congenital disorders of glycosylation) as well as congenital muscular dystrophies with neuronal-cell-migration defects have been elucidated with the help of yeast.
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Affiliation(s)
- Ludwig Lehle
- Lehrstuhl für Zellbiologie und Pflanzenphysiologie, Universität Regensburg, Universitätstrasse 31, 93053 Regensburg, Germany.
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275
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Thayer DA, Yu HN, Galan MC, Wong CH. A general strategy toward S-linked glycopeptides. Angew Chem Int Ed Engl 2006; 44:4596-9. [PMID: 15991213 DOI: 10.1002/anie.200500090] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Desiree A Thayer
- Department of Chemistry and Skaggs Institute for Chemical Biology, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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276
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Birdwell KR, Austell TL, Black RS, Jorgenson JW, Hiskey RG. Evaluation of Proteolytically Released Carbohydrate-Containing Peptides of Bovine Prothrombin Fragment 1 Using Electrospray Ionization Mass Spectrometry and Capillary Electrophoresis. J LIQ CHROMATOGR R T 2006. [DOI: 10.1080/10826079708010953] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Keisa R. Birdwell
- a Department of Chemistry , University of North Carolina , Chapel Hill, CB, #3290, Venable Hall Chapel Hill, North Carolina 27599
| | - Todd L. Austell
- a Department of Chemistry , University of North Carolina , Chapel Hill, CB, #3290, Venable Hall Chapel Hill, North Carolina 27599
| | - Roderick S. Black
- a Department of Chemistry , University of North Carolina , Chapel Hill, CB, #3290, Venable Hall Chapel Hill, North Carolina 27599
| | - James W. Jorgenson
- a Department of Chemistry , University of North Carolina , Chapel Hill, CB, #3290, Venable Hall Chapel Hill, North Carolina 27599
| | - Richard G. Hiskey
- a Department of Chemistry , University of North Carolina , Chapel Hill, CB, #3290, Venable Hall Chapel Hill, North Carolina 27599
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277
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Kelebekli L, Çelik M, Şahin E, Kara Y, Balci M. Stereospecific synthesis of a new class of aminocyclitol with the conduramine D-2 configuration. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.07.108] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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278
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Kataoka H, Yasuda M, Iyori M, Kiura K, Narita M, Nakata T, Shibata KI. Roles of N-linked glycans in the recognition of microbial lipopeptides and lipoproteins by TLR2. Cell Microbiol 2006; 8:1199-209. [PMID: 16819971 DOI: 10.1111/j.1462-5822.2006.00702.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Details of roles of carbohydrates attached to Toll-like receptors (TLRs) in the recognition of pathogen-associated molecular patterns and in the formation of the functional receptor complex still remain unknown. This study was designed to determine whether the glycans linked at Asn114, Asn199, Asn414 and Asn442 residues of TLR2 ectodomain were involved in the recognition of diacylated lipopeptide and lipoprotein. Single and multiple mutants were transfected into human embryonic kidney (HEK) 293 cells together with a NF-kappaB luciferase reporter plasmid. All of these mutants were expressed on the surface. SDS-PAGE of the transfectants demonstrated that these mutants migrated lower than wild-type TLR2 and their molecular masses decreased as the number of mutated Asn residues increased. TLR2(N114A), TLR2(N199A) and TLR2(N414A) as well as wild-type TLR2 induced NF-kappaB activation when stimulated with these ligands, whereas TLR2(N442A) failed to induce NF-kappaB activation. All of triple and quadruple mutants failed to induce NF-kappaB activation, but were associated with both wild-type TLR2 and TLR6 in the transfectants. TLR2(N114A,N199A), TLR2(N114A,N414A) and, to a lesser extent, TLR2(N114A,N442A), in which two N-linked glycans are speculated to be exposed to the concave surface of TLR2 solenoid, not only induce NF-kappaB activation but also are associated with wild-type TLR2 and TLR6. These results suggest that the glycan at Asn442 and at least two N-linked glycans speculated to be exposed to the concave surface of TLR2 solenoid are involved in the recognition of ligands by TLR2 and/or in formation or maturation of a functional TLR2 receptor complex.
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Affiliation(s)
- Hideo Kataoka
- Laboratory of Oral Molecular Microbiology, Department of Oral Pathobiological Science, Hokkaido University Graduate School of Dental Medicine, Nishi 7, Kita 13, Kita-ku, Sapporo 060-8586, Japan
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279
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Hiro S, Usuki Y, Iio H. Synthesis of the sugar moiety of TIME-EA4, a glycopeptide isolated from silkworm diapause eggs. Carbohydr Res 2006; 341:1796-802. [PMID: 16697998 DOI: 10.1016/j.carres.2006.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 03/26/2006] [Accepted: 04/12/2006] [Indexed: 11/22/2022]
Abstract
We describe the efficient synthesis of the tetrasaccharide, 2-O-acetyl-3,4,6-tri-O-benzyl-alpha-D-mannopyranosyl-(1-->6)-2,4-di-O-acetyl-3-O-allyl-beta-D-mannopyranosyl-(1-->4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl-(1-->4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl azide, which is the protected form of the sugar unit of TIME-EA4 that is isolated from the diapausing eggs of the silkworm, Bombyx mori. The beta-linked D-mannoside of the tetrasaccharide was obtained using the conventional oxidation-reduction method for inversion of the configuration at the C-2 hydroxyl group of beta-D-glucoside. The reduction was effected with NaBH(4) in a methanolic solution in a ratio of 98:2 in favor of the beta-D-mannoside that was obtained in 87% yield.
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Affiliation(s)
- Shouji Hiro
- Department of Material Science, Graduate School of Science, Osaka City University, Japan
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280
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Awad L, Demange R, Zhu YH, Vogel P. The use of levoglucosenone and isolevoglucosenone as templates for the construction of C-linked disaccharides. Carbohydr Res 2006; 341:1235-52. [PMID: 16678805 DOI: 10.1016/j.carres.2006.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 04/10/2006] [Accepted: 04/12/2006] [Indexed: 11/19/2022]
Abstract
Because of their functionalities (enone, ketone, and acetal) and their bicyclic structure (steric factors), levoglucosenone (1,6-anhydro-3,4-dideoxy-beta-D-glycero-hex-3-enopyran-2-ulose) and isolevoglucosenone (1,6-anhydro-2,3-dideoxy-beta-D-glycero-hex-3-enopyran-4-ulose) are useful templates for the convergent and combinatorial synthesis of (1-->2), (1-->3), and (1-->4)-linked C-disaccharides in reactions combining them with sugar-derived carbaldehydes. Synthetic methods relying on conjugate nucleophilic additions of these enones, their combination with aluminum reagents and aldehydes (Baylis-Hillman reaction) and modified Takai-Hiyama-Nozaki-Kishi couplings of enol triflates derived from them with sugar-derived aldehydes are reviewed. Highly stereoselective methods have thus been developed. These allow the generation of disaccharide mimetics with a high molecular diversity.
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Affiliation(s)
- Loay Awad
- Laboratoire de Glycochimie et de Synthèse Asymétrique, Ecole Polytechnique Fédérale de Lausanne (EPFL), BCH, CH-1015 Lausanne, Switzerland.
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281
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Abstract
Synthetic carbohydrates and glycoconjugates are used to study their roles in biological important processes such as inflammation, cell-cell recognition, immunological response, metastasis, and fertilization. The development of an automated oligosaccharide synthesizer greatly accelerates the assembly of complex, naturally occurring carbohydrates as well as chemically modified oligosaccharide structures and promises to have major impact on the field of glycobiology. Tools such as microarrays, surface plasmon resonance spectroscopy, and fluorescent carbohydrate conjugates to map interactions of carbohydrates in biological systems are presented. Case studies of the successful application of carbohydrates as active agents are discussed, for example, fully synthetic oligosaccharide vaccines to combat tropical diseases (e.g., malaria), bacterial infections (e.g., tuberculosis), viral infections such as HIV, and cancer. Aminoglycosides serve as examples of drugs acting through carbohydrate-nucleic-acid interactions, while heparin works by carbohydrate-protein interactions. A general, modular strategy for the complete stereoselective synthesis of defined heparin oligosaccharides is presented. A carbohydrate-functionalized fluorescent polymer has been shown to detect miniscule amounts of bacteria faster than commonly used methods.
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Affiliation(s)
- Daniel B Werz
- Laboratory for Organic Chemistry, Swiss Federal Institute of Technology Zürich, ETH-Hönggerberg, HCI F315, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
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282
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Drakakaki G, Marcel S, Arcalis E, Altmann F, Gonzalez-Melendi P, Fischer R, Christou P, Stoger E. The intracellular fate of a recombinant protein is tissue dependent. PLANT PHYSIOLOGY 2006; 141:578-86. [PMID: 16632592 PMCID: PMC1475444 DOI: 10.1104/pp.106.076661] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Recombinant proteins directed to the secretory pathway in plants require a signal peptide for entry into the endoplasmic reticulum. In the absence of further targeting information, such proteins are generally secreted via the default pathway to the apoplast. This has been well documented in protoplasts and leaf tissue, but the trafficking of recombinant proteins in seeds and other storage tissues has rarely been investigated. We used Aspergillus niger phytase as a model glycoprotein to compare the intracellular fate of a recombinant protein in the leaves and seeds of rice (Oryza sativa). Using fluorescence and electron microscopy we showed that the recombinant protein was efficiently secreted from leaf cells as expected. In contrast, within endosperm cells it was retained in endoplasmic reticulum-derived prolamin bodies and protein storage vacuoles. Consistent with our immunolocalization data, the phytase produced in endosperm cells possessed oligomannose and vacuolar-type N-glycans [Man(3)(Xyl)(Fuc)GlcNAc(2)], whereas the phytase produced in leaves contained predominantly secretion-type N-glycans [GlcNAc(2)Man(3)(Xyl)(Fuc)GlcNAc(2)]. The latter could not be detected in preparations of the endosperm-derived phytase. Our results show that the intracellular deposition and modification of a recombinant protein is tissue dependent.
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Affiliation(s)
- Georgia Drakakaki
- Institute for Molecular Biotechnology, Biology VII, Aachen University, 52074 Aachen, Germany
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283
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Lekka M, Laidler P, Labedź M, Kulik AJ, Lekki J, Zajac W, Stachura Z. Specific Detection of Glycans on a Plasma Membrane of Living Cells with Atomic Force Microscopy. ACTA ACUST UNITED AC 2006; 13:505-12. [PMID: 16720271 DOI: 10.1016/j.chembiol.2006.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 03/13/2006] [Accepted: 03/13/2006] [Indexed: 01/30/2023]
Abstract
Among the many alterations of cancer cells is the expression of different surface oligosaccharides. In this work, oligosaccharide expression in living cells (cancer and reference ones) was studied with atomic force microscopy by using lectins as probes. The unbinding force obtained for the same lectin type (concanavalin A or Sambucus nigra) suggested slightly dissimilar structures of binding sites of the same ligand type. For the lectin from Phaseolus vulgaris, a much larger unbinding force indicated a distinct structure of the binding site in cancer cells. The unbinding probability confirmed a higher content of both sialic acid and mannose-containing ligands in cancer and reference cells, respectively. These results demonstrate the potential of atomic force microscopy to directly probe the presence of molecules on a living cell surface, together with the quantitative description of their expression.
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Affiliation(s)
- Małgorzata Lekka
- The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland.
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284
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Bouvet VR, Ben RN. A Short and Economical Synthesis of Orthogonally Protected C-Linked 2-Deoxy-2-acetamido-α-d-galactopyranose Derivatives. J Org Chem 2006; 71:3619-22. [PMID: 16626151 DOI: 10.1021/jo051938j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A short and high-yielding synthesis has been devised to prepare C-linked 2-deoxy-2-acetamido-alpha-D-galactopyranose derivative 3. One of the main advantages of this approach is that it employs commercially available and inexpensive d-glucosamine as the starting material. The key steps include a highly stereoselective C-allylation followed by epimerization of the C-4 hydroxyl group. Building block 3 and orthogonally protected C-linked 2-deoxy-2-acetamido-alpha-D-galactopyranose derivative 2 were obtained in 44% overall yield (six steps) and 29% overall yield (eight steps), respectively. This represents a significant improvement over previously reported syntheses.
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Affiliation(s)
- Vincent R Bouvet
- Department of Chemistry, University of Ottawa, Ottawa, Ontario KIN 6N5, Canada
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285
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Lazarević D, Thiem J. Artificial N-functionalized UDP-glucosamine analogues as modified substrates for N-acetylglucosaminyl transferases. Carbohydr Res 2006; 341:569-76. [PMID: 16445891 DOI: 10.1016/j.carres.2006.01.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 12/06/2005] [Accepted: 01/15/2006] [Indexed: 11/26/2022]
Abstract
Analogues of UDP-GlcNAc modified at the 2-acetamido group of the GlcNAc moiety were prepared in order to study their role in the mechanism of N-acetylglucosaminyl transferase mediated glycosylation reactions. The structural analogues with N-formyl-, N-propionyl-, N-butyryl- and N-isobutyryl-groups were synthesized, utilizing the morpholidate coupling method starting from d-glucosaminyl-1-phosphate after selective N-acylation of its amino group with the appropriate N-acyloxysuccinimide esters as well as a chlorinated formylformiate.
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Affiliation(s)
- Daniel Lazarević
- Institut für Organische Chemie, Universität Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
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286
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Takemori N, Komori N, Matsumoto H. Highly sensitive multistage mass spectrometry enables small-scale analysis of protein glycosylation from two-dimensional polyacrylamide gels. Electrophoresis 2006; 27:1394-406. [PMID: 16502458 DOI: 10.1002/elps.200500324] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Structural characterization of glycoproteins remains among the most challenging areas of glycomics due to the requirement of large quantities of samples and laborious biochemical steps involved in the analytical procedure. Here we report the structural characterization of glycoproteins separated on a 2-D gel by using a MALDI-QIT-TOF MS where QIT is quadrupole IT. The combination of MALDI-ion source and QIT appears to generate a unique tendency to cause fragmentation of glycopeptides without collision-induced dissociation. The majority of such fragmentations observed in our study result from the cleavage of sugar linkages, but not of peptide-peptide or peptide-sugar linkages. This unique feature allows us to perform pseudo-MS3 analysis of a fragmented glycopeptide. A small gel spot of a glycoprotein in the abundance range of low picomoles was enough for the mass spectrometer to analyze fragmentation pathway of the sugar linkage and peptide backbone. In this study, we demonstrate direct determination of glycosylation sites and N-linked glycan-sequences of the tryptic glycopeptides of Drosophila glycoproteins. Glycopeptides with various MWs up to approximately 4000 Da were suitable for structural analysis, including its attachment site and the amino acid sequence, of the glycopeptide through multistage mass spectrometric analysis.
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Affiliation(s)
- Nobuaki Takemori
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA
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287
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Jiménez-Farfán D, Guevara J, Zenteno E, Hernández-Guerrero JC. Alteration of the sialylation pattern of the murine tooth germ after ethanol exposure. ACTA ACUST UNITED AC 2006; 73:980-8. [PMID: 16323169 DOI: 10.1002/bdra.20198] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Ethanol consumption during pregnancy leads to changes in murine dental morphogenesis, dental size, cellular differentiation, enamel mineralization, and delayed eruption. It has been proposed that glycoproteins play a role during embryonic dental development that may determine the dental morphological pattern and extracellular matrix secretion. O-glycosylation and sialylation appear to actively participate in the differentiation and maturation processes. Because glycosylation may be affected by teratogens that can alter the maturation of several organisms, in this work we describe the main modifications of the sialylation pattern in prenatal day (PD) 18.5 murine tooth germs exposed to ethanol. METHODS Pregnant female mice were divided into groups that were given 15% or 20% ethanol solutions, or water as a control. The histochemistry of tooth germs from PD 18.5 fetuses was revealed with lectins specific for sialic acid (Neu5Ac), such as Sambucus nigra (SNA), Maackia amurensis (MAA), and Machrobrachium rosenbergii (MRL), and for sialylated-O-glycosidically linked glycans, such as Amaranthus leucocarpus (ALL). RESULTS The basement membrane, preameloblasts, inner-enamel epithelium, preodontoblasts, and subodontoblastic cells of the test groups showed changes in labeling according to the 4 lectins used. Intranuclear staining was observed with SNA (specific for Neu5Acalpha2,6Gal/GalNAc) in the control group, but this was reduced in the test groups. The nuclei of dental papillary cells under the experimental conditions were stained with MAA (Neu5Acalpha2,3Gal). CONCLUSIONS Dental development involves different types of sialylated O-glycosidically linked glycans that are likely to regulate cell-to-cell and cell-to-matrix interactions. Our results suggest that ethanol consumption during pregnancy alters the sialylation pattern during murine dental morphogenesis.
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Affiliation(s)
- Dolores Jiménez-Farfán
- Laboratorio de Inmunología, División de Estudios de Posgrado e Investigación, DEPeI, Facultad de Odontología, Universidad Nacional Autónoma de México, Ciudad de México, México
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288
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Raju TS, Scallon BJ. Glycosylation in the Fc domain of IgG increases resistance to proteolytic cleavage by papain. Biochem Biophys Res Commun 2006; 341:797-803. [PMID: 16442075 DOI: 10.1016/j.bbrc.2006.01.030] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 01/09/2006] [Indexed: 11/24/2022]
Abstract
IgG antibodies (Abs) and fragments of IgG Abs are becoming major biotherapeutics to treat an assortment of human diseases. Commonly prepared fragments of IgGs include Fc, Fab, and F(ab')2 fragments, all of which can be made using the sulfhydryl protease papain, although prolonged digestion times and/or excessive amounts of papain typically result in further cleavage of the Fc domain into smaller fragments. During our attempts to use papain to isolate Fc fragments from different IgG monoclonal Abs, it was observed that prior removal of Fc glycans resulted in a faster rate of papain-mediated degradation of the Fc domain. Subsequent time-course experiments comparing glycosylated and deglycosylated versions of IgG antibodies showed that the majority of molecules in a deglycosylated IgG sample were converted into Fab, Fc, and smaller Fc fragments in less than one hour, whereas the original glycosylated IgG required more than two hours to convert into a comparable amount of Fab and Fc fragments. Furthermore, whereas papain digestion converted almost all of a deglycosylated Fc fragment into smaller fragments of approximately 10 and approximately 12 kDa within 4 h, more than 40% of a glycosylated Fc fragment remained intact even after 24 h of digestion. These results indicate that the presence of CH(2) domain glycans in either IgGs or purified Fc fragments increases resistance to papain digestion. Increased sensitivity of non-glycosylated Fc domains to papain is consistent with the Fc domains lacking a defined structure, as exemplified by their inability to bind Fcgamma receptors, since misfolded proteins are often degraded by proteases because of increased accessibility of their proteolytic cleavage sites. Based on these observations it is possible to use papain sensitivity as a means of assessing proper Fc structure of IgG molecules.
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Affiliation(s)
- T Shantha Raju
- Discovery Research, Centocor R&D Inc., 145 King of Prussia Road, Radnor, PA 19087, USA.
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289
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Witt KA, Davis TP. CNS drug delivery: opioid peptides and the blood-brain barrier. AAPS JOURNAL 2006; 8:E76-88. [PMID: 16584136 PMCID: PMC2751425 DOI: 10.1208/aapsj080109] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Peptides are key regulators in cellular and intercellular physiological responses and possess enormous promise for the treatment of pathological conditions. Opioid peptide activity within the central nervous system (CNS) is of particular interest for the treatment of pain owing to the elevated potency of peptides and the centrally mediated actions of pain processes. Despite this potential, peptides have seen limited use as clinically viable drugs for the treatment of pain. Reasons for the limited use are primarily based in the physiochemical and biochemical nature of peptides. Numerous approaches have been devised in an attempt to improve peptide drug delivery to the brain, with variable results. This review describes different approaches to peptide design/modification and provides examples of the value of these strategies to CNS delivery of peptide drugs. The various modes of modification of therapeutic peptides may be amalgamated, creating more efficacious "hybrid" peptides, with synergistic delivery to the CNS. The ongoing development of these strategies provides promise that peptide drugs may be useful for the treatment of pain and other neurologically-based disease states in the future.
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Affiliation(s)
- Ken A. Witt
- />Pharmaceutical Sciences, School of Pharmacy, Southern Illinois University, Edwardsville, 200 University Park Drive, 62026 Edwardsville, IL. USA
| | - Thomas P. Davis
- />Department of Medical Pharmacology, College of Medicine, The University of Arizona, LSN 542, 1501 N. Campbell Avenue, P.O. Box 245050, 85724 Tucson, Arizona
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290
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Mitra N, Sinha S, Ramya TNC, Surolia A. N-linked oligosaccharides as outfitters for glycoprotein folding, form and function. Trends Biochem Sci 2006; 31:156-63. [PMID: 16473013 DOI: 10.1016/j.tibs.2006.01.003] [Citation(s) in RCA: 232] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 01/06/2006] [Accepted: 01/30/2006] [Indexed: 01/27/2023]
Abstract
Glycosylation, particularly N-linked glycosylation, profoundly affects protein folding, oligomerization and stability. The increased efficiency of folding of glycosylated proteins could be due to the chaperone-like activity of glycans, which is observed even when the glycan is not attached to the protein. Covalently linked glycans could also facilitate oligomerization by mediating inter-subunit interactions in the protein or stabilizing the oligomer in other ways. Glycosylation also affects the rate of fibril formation in prion proteins: N-glycans reduce the rate of fibril formation, and O-glycans affect the rate either way depending on factors such as position and orientation. It has yet to be determined whether there is any correlation among the sites of glycosylation and the ensuing effect in multiply glycosylated proteins. It is also not apparent whether there is a common pattern in the conservation of glycans in a related family of glycoproteins, but it is evident that glycosylation is a multifaceted post-translational modification. Indeed, glycosylation serves to "outfit" proteins for fold-function balance.
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Affiliation(s)
- Nivedita Mitra
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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291
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Dengjel J, Stevanovic S. Naturally Presented MHC Ligands Carrying Glycans. Transfus Med Hemother 2006. [DOI: 10.1159/000090194] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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292
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Uhrig ML, Manzano VE, Varela O. Stereoselective Synthesis of 3-Deoxy-4-S-(1→4)-Thiodisaccharides and Their Inhibitory Activities Towards β-Glycoside Hydrolases. European J Org Chem 2006. [DOI: 10.1002/ejoc.200500457] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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293
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Röhrig CH, Retz OA, Hareng L, Hartung T, Schmidt RR. A new strategy for the synthesis of dinucleotides loaded with glycosylated amino acids--investigations on in vitro non-natural amino acid mutagenesis for glycoprotein synthesis. Chembiochem 2005; 6:1805-16. [PMID: 16142818 DOI: 10.1002/cbic.200500079] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The in vitro non-natural amino acid mutagenesis method provides the opportunity to introduce non-natural amino acids site-specifically into proteins. To this end, a chemically synthesised aminoacylated dinucleotide is enzymatically ligated to a truncated suppressor transfer RNA. The loaded suppressor tRNA is then used in translation reactions to read an internal stop codon. Here we report an advanced and general strategy for the synthesis of the aminoacyl dinucleotide. The protecting group pattern developed for the dinucleotide facilitates highly efficient aminoacylation, followed by one-step global deprotection. The strategy was applied to the synthesis of dinucleotides loaded with 2-acetamido-2-deoxy-glycosylated amino acids, including N- and O-beta-glycosides and O- and C-alpha-glycosides of amino acids, thus enabling the extension of in vitro non-natural amino acid mutagenesis towards the synthesis of natural glycoproteins of high biological interest. We demonstrate the incorporation of the glycosylamino acids--although with low suppression efficiency--into the human interleukin granulocyte-colony stimulating factor (hG-CSF), as verified by the ELISA technique.
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Affiliation(s)
- Christoph H Röhrig
- Department of Chemistry, University of Konstanz, Fach M 725, 78457 Konstanz, Germany
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294
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Seddas P, Boissinot S. Glycosylation of beet western yellows virus proteins is implicated in the aphid transmission of the virus. Arch Virol 2005; 151:967-84. [PMID: 16320008 DOI: 10.1007/s00705-005-0669-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Accepted: 09/24/2005] [Indexed: 01/22/2023]
Abstract
Beet western yellows virus relies on the aphid M. persicae for its transmission in a persistent and circulative mode. To be transmitted, the virus must cross the midgut and the accessory salivary gland epithelial barriers by a transcytosis mechanism where vector receptors interact with virions. The aphid and the peptidic viral determinants implicated in this interaction mechanism have been studied. In this paper, we report that the coat and the readthrough proteins that constitute the capsid of this virus are glycosylated. Modification of the glucidic core of these structural viral proteins by oxidation with sodium metaperiodate or deglycosylation with N-glycosidase F or alpha-D-galactosidase abrogates the aphid transmission of the virus. Aphid transmission could also be inhibited by lectins directed against alpha-D-galactose when aphids were allowed to acquire virus on artificial membranes. These results suggest that the glucidic cores of the capsid proteins of beet western yellows virus contain alpha-D-galactose residues that are implicated in virus-aphid interaction and promote aphid transmission of the virus.
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Affiliation(s)
- P Seddas
- Institut National de la Recherche Agronomique, Unité de Recherche Biologie des Interactions Virus/Vecteur, Colmar, France.
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295
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Daly R, Hearn MTW. Expression of the human activin type I and II receptor extracellular domains in Pichia pastoris. Protein Expr Purif 2005; 46:456-67. [PMID: 16309921 DOI: 10.1016/j.pep.2005.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 09/28/2005] [Accepted: 10/01/2005] [Indexed: 11/21/2022]
Abstract
Methods for the expression in Pichia pastoris and purification of the human activin receptor type I and II extracellular domains (ARIa/ARIb-ECDs, ARIIA/ARIIB-ECDs) are described. Key experimental aspects are also documented of the vector transformation methodology and the binding characteristics of these ECDs with activin A and inhibin. The cDNA constructs for these ECDs contained a C-terminal His6-tag with either the native signal (N) or the yeast alpha mating factor (alphaMF) sequence and were introduced into the pPICZ expression vector either as a single-copy or as a four-copy expression cassette. Hyper-resistant transformants (zeo(R): 500 microg/mL) generated from the cassette containing a single copy of the expression vector gave the stronger signal intensity with a DNA dot-blot screening assay. These transformants also produced higher quantities of the corresponding recombinant protein compared to transformants using the four-copy cassette vector. All receptor-ECD proteins expressed were found to be heterogeneously glycosylated, whereby the ARIIA-ECD and ARIIB-ECD had undergone two Asn-linked glycosylation events and the ARIb-ECD a single event. By SDS-PAGE, the de-glycosylated proteins migrated larger than the expected core size, indicating that they may have undergone O-linked glycosylation. Biacore-based procedures with the glycosylated and de-glycosylated ARIIA-ECD were employed to determine the kinetic and equilibrium binding parameters for the interaction with activin A and inhibin. The glycosylated ARIIA-ECD bound to activin A with a KD of 11.9 nM and inhibin with a KD of 21.1 nM. Although glycosylation of ARIIA-ECD was not strictly required for high affinity interactions with activin A or inhibin, it markedly improved the overall stability of the ARIIA-ECD.
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Affiliation(s)
- Rachel Daly
- ARC Special Research Centre for Green Chemistry, Monash University, Wellington Road, Clayton, Vic. 3800, Australia
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296
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Liu D, Cramer CC, Scafidi J, Davis AE. N-linked glycosylation at Asn3 and the positively charged residues within the amino-terminal domain of the c1 inhibitor are required for interaction of the C1 Inhibitor with Salmonella enterica serovar typhimurium lipopolysaccharide and lipid A. Infect Immun 2005; 73:4478-87. [PMID: 16040958 PMCID: PMC1201182 DOI: 10.1128/iai.73.8.4478-4487.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The C1 inhibitor (C1INH), a plasma complement regulatory protein, prevents endotoxin shock, at least partially via the direct interaction of its amino-terminal heavily glycosylated nonserpin region with gram-negative bacterial lipopolysaccharide (LPS). To further characterize the potential LPS-binding site(s) within the amino-terminal domain, mutations were introduced into C1INH at the three N-linked glycosylation sites and at the four positively charged amino acid residues. A mutant in which Asn(3) was replaced with Ala was markedly less effective in its binding to LPS, while substitution of Asn(47) or Asn(59) had little effect on binding. The mutation of C1INH at all four positively charged amino acid residues (Arg(18), Lys(22), Lys(30), and Lys(55)) resulted in near-complete failure to interact with LPS. The C1INH mutants that did not bind to LPS also did not suppress LPS binding or LPS-induced up-regulation of tumor necrosis factor alpha mRNA expression in RAW 264.7 macrophages. In addition, the binding of C1INH mutants to diphosphoryl lipid A was decreased in comparison with that of recombinant wild-type C1INH. Therefore, the interaction of C1INH with gram-negative bacterial LPS is dependent both on the N-linked carbohydrate at Asn(3) and on the positively charged residues within the amino-terminal domain.
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Affiliation(s)
- Dongxu Liu
- The CBR Institute for Biomedical Research, Harvard Medical School, 800 Huntington Avenue, Boston, MA 02115, USA
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297
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Abstract
In recent years, there have been several important advancements in the development of neuropeptide therapeutics. Nevertheless, the targeting of peptide drugs to the CNS remains a formidable obstacle. Delivery of peptide drugs is limited by their poor bioavailability to the brain due to low metabolic stability, high clearance by the liver, and the presence of the blood brain barrier (BBB). Multiple strategies have been devised in an attempt to improve peptide drug delivery to the brain, with variable results. In this review, we discuss several of the strategies that have been used to improve both bioavailability and BBB transport, with an emphasis on antibody based vector delivery, useful for large peptides/small proteins, and glycosylation, useful for small peptides. Further development of these delivery methods may finally enable peptide drugs to be useful for the treatment of neurological disease states.
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Affiliation(s)
- Richard D Egleton
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, USA.
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298
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Thayer DA, Yu HN, Galan MC, Wong CH. A General Strategy toward S-Linked Glycopeptides. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200500090] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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299
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Andriuzzi O, Gravier-Pelletier C, Vogel P, Le Merrer Y. Synthesis and glycosidase inhibitory activity of new penta-substituted C8-glycomimetics. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.05.066] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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300
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Tani F, Shirai N, Nakanishi Y, Yasumoto K, Kitabatake N. Role of the carbohydrate chain and two phosphate moieties in the heat-induced aggregation of hen ovalbumin. Biosci Biotechnol Biochem 2005; 68:2466-76. [PMID: 15618616 DOI: 10.1271/bbb.68.2466] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We investigated the effect of the carbohydrate chain and two phosphate moieties on heat-induced aggregation of hen ovalbumin. The dephosphorylated form of ovalbumin was obtained by treating the original protein with acid phosphatase. The single carbohydrate chain was removed by digestion of heat-denatured ovalbumin with glycopeptidase F, and the resulting polypeptide without this carbohydrate chain was correctly refolded to acquire protease-resistance. Thermal unfolding can be approximated by a mechanism involving a two-state transition between the folded and unfolded states with a midpoint temperature of 76 degrees C for the original form, of 74 degrees C for the dephosphorylated form, and of 71 degrees C for the carbohydrate-free form. The conformational stability of the original form was higher than that of the carbohydrate-free form. When the three forms of ovalbumin were heated to 80 degrees C and then cooled rapidly in an ice bath, the polypeptide chains were compactly collapsed to metastable intermediates with secondary structures whose properties were indistinguishable. Upon incubation at 60 degrees C, renaturation was possible for a large portion of the intermediates of the original form, but for only a small portion of those of the carbohydrate-free form. Light scattering experiments showed that in the presence of sulfate anions, the intermediates of the carbohydrate-free form aggregated to a greater extent than did those of the original form. The intermediates of the carbohydrate-free form bound to the chaperonin GroEL with about 10-fold higher affinity than those of the original form. It follows that the carbohydrate chain and the two phosphate moieties do not affect hydrophobic collapse in the kinetic refolding of hen ovalbumin but play an important role in the slow rearrangement. They block the off-pathway reaction that competes with correct refolding by effectively decreasing surface hydrophobicity.
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Affiliation(s)
- Fumito Tani
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Goka-sho, Uji, Kyoto 611-0011, Japan.
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