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Thomas J Tolbert - One of the best experts on this subject based on the ideXlab platform.
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on resin convergent synthesis of a glycopeptide from hiv gp120 containing a high Mannose type n linked Oligosaccharide
Methods of Molecular Biology, 2011Co-Authors: Rui Chen, Thomas J TolbertAbstract:Homogenous N-linked glycopeptides are valuable materials for biochemical, structural and medicinal studies to help understand the specific roles of N-linked glycosylation (4) and facilitate the development of N-linked glycopeptide based vaccines and therapeutics (5). However, the starting materials of glycopeptide synthesis, large N-linked Oligosaccharides, are often difficult to obtain from biological systems and are also difficult to chemically synthesize (6–11). In addition, the coupling of large, bulky N-linked Oligosaccharides to peptides can be a low yielding reaction that is prone to aspartimide formation (12–13). Because of this it is crucial to utilize an efficient method for N-linked glycopeptide synthesis which does not waste valuable N-linked Oligosaccharide starting materials. The method of N-linked glycopeptide synthesis (1) described here effectively combines the advantages of both solid phase peptide synthesis (SPPS) (14) and in-solution Lansbury aspartylation (15–16) by introducing the glycosylation site via glycosylamine coupling to partially protected, full-length peptides on solid phase support (1). As described in Fig. 1, the full length non-glycosylated peptide sequence is first built via SPPS. At the desired glycosylation site, a 2-phenylisopropyl (PhiPr) (17) orthogonally protected Asp residue is incorporated. The PhiPr protecting group efficiently suppresses aspartimide formation during the construction of the peptide unlike other orthogonal protecting groups such as allyl esters (1, 18–20). Next, the PhiPr protecting group is selectively removed on-resin to free the carboxylic acid side chain of the Asp residue, which allows the introduction of the N-linked Oligosaccharide. Then a glycosylamine, such as Man8GlcNAc2NH2, 2, is coupled to the free Asp side chain on-resin. This key step has been optimized for both the monosaccharide N-acetylglucosamine (GlcNAcNH2) and a high Mannose Oligosaccharide (Man8GlcNAc2NH2, 2) on aspartimide prone peptide sequences, and satisfying glycosylation yields have been achieved (1). At the end of the synthesis, final deprotection and resin cleavage provide the desired N-linked glycopeptide. An important aspect of this strategy is that excess N-linked Oligosaccharides can be utilized to drive the glycosylation reaction on-resin and un-reacted, valuable Oligosaccharide can be conveniently recovered after the on-resin glycosylamine coupling reaction by filtration and silica gel purification. The recovered Oligosaccharide can then be reused in later syntheses, increasing the efficiency of this method (1). Fig. 1 Strategy for on-resin convergent synthesis of N-linked high Mannose Oligosaccharide containing glycopeptides. Here this strategy for N-linked glycopeptide synthesis is demonstrated by the synthesis of a glycosylated form of peptide T (ASTTTNYT) containing the high Mannose Oligosaccharide Man8GlcNAc2, 1. Peptide T is a fragment of the HIV-1 envelope protein gp120 consisting of residues 185 to 192 which contains a naturally occurring N-linked glycosylation site consensus sequence (2–3).
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study of on resin convergent synthesis of n linked glycopeptides containing a large high Mannose n linked Oligosaccharide
Journal of the American Chemical Society, 2010Co-Authors: Rui Chen, Thomas J TolbertAbstract:Here we present a convergent on-resin glycosylamine coupling strategy for solid phase N-linked glycopeptide synthesis, and apply it to the synthesis of high Mannose containing glycopeptides. In this strategy, the 2-phenylisopropyl protecting group is used as an orthogonal handle to create glycosylation sites on-resin after synthesis of nonglycosylated peptides. In addition to allowing selective deprotection of aspartic acid residues for creation of glycosylation sites, the 2-phenylisopropyl protecting group also efficiently suppresses aspartimide formation during peptide synthesis. The key step of on-resin glycosylamine coupling to an aspartic acid residue was first optimized for a small sugar, N-acetylglucosamine, and then applied to a much larger high Mannose Oligosaccharide, Man8GlcNAc2. Satisfying coupling yields were obtained for both small and large sugars. The use of on-resin glycosylamine coupling simplifies purification of N-linked glycopeptides, and also allows convenient recovery of unreacted v...
José J. Reina - One of the best experts on this subject based on the ideXlab platform.
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Straightforward synthesis of Man9, the relevant epitope of the high-Mannose Oligosaccharide.
Organic & biomolecular chemistry, 2017Co-Authors: Javier Ramos-soriano, M. Carmen De La Fuente, Noelia De La Cruz, Rute Cunha Figueiredo, Javier Rojo, José J. ReinaAbstract:The high-Mannose Oligosaccharide (or its corresponding Man9 epitope) is the most abundant structure present in pathogen envelope glycoproteins. These glycans play a key role in the pathogenesis of several pathogens and also in the communication with the immune system. Understanding the mechanism of action of these glycans requires the access to pure and chemically well-defined structures in reasonable amounts. The synthesis of these complex branched Oligosaccharides is not trivial and few syntheses are reported in the literature with several synthetic and purification steps and low overall yields. In this work, we described a very efficient synthetic alternative to access this relevant Man9 epitope in a very straightforward manner.
Rui Chen - One of the best experts on this subject based on the ideXlab platform.
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on resin convergent synthesis of a glycopeptide from hiv gp120 containing a high Mannose type n linked Oligosaccharide
Methods of Molecular Biology, 2011Co-Authors: Rui Chen, Thomas J TolbertAbstract:Homogenous N-linked glycopeptides are valuable materials for biochemical, structural and medicinal studies to help understand the specific roles of N-linked glycosylation (4) and facilitate the development of N-linked glycopeptide based vaccines and therapeutics (5). However, the starting materials of glycopeptide synthesis, large N-linked Oligosaccharides, are often difficult to obtain from biological systems and are also difficult to chemically synthesize (6–11). In addition, the coupling of large, bulky N-linked Oligosaccharides to peptides can be a low yielding reaction that is prone to aspartimide formation (12–13). Because of this it is crucial to utilize an efficient method for N-linked glycopeptide synthesis which does not waste valuable N-linked Oligosaccharide starting materials. The method of N-linked glycopeptide synthesis (1) described here effectively combines the advantages of both solid phase peptide synthesis (SPPS) (14) and in-solution Lansbury aspartylation (15–16) by introducing the glycosylation site via glycosylamine coupling to partially protected, full-length peptides on solid phase support (1). As described in Fig. 1, the full length non-glycosylated peptide sequence is first built via SPPS. At the desired glycosylation site, a 2-phenylisopropyl (PhiPr) (17) orthogonally protected Asp residue is incorporated. The PhiPr protecting group efficiently suppresses aspartimide formation during the construction of the peptide unlike other orthogonal protecting groups such as allyl esters (1, 18–20). Next, the PhiPr protecting group is selectively removed on-resin to free the carboxylic acid side chain of the Asp residue, which allows the introduction of the N-linked Oligosaccharide. Then a glycosylamine, such as Man8GlcNAc2NH2, 2, is coupled to the free Asp side chain on-resin. This key step has been optimized for both the monosaccharide N-acetylglucosamine (GlcNAcNH2) and a high Mannose Oligosaccharide (Man8GlcNAc2NH2, 2) on aspartimide prone peptide sequences, and satisfying glycosylation yields have been achieved (1). At the end of the synthesis, final deprotection and resin cleavage provide the desired N-linked glycopeptide. An important aspect of this strategy is that excess N-linked Oligosaccharides can be utilized to drive the glycosylation reaction on-resin and un-reacted, valuable Oligosaccharide can be conveniently recovered after the on-resin glycosylamine coupling reaction by filtration and silica gel purification. The recovered Oligosaccharide can then be reused in later syntheses, increasing the efficiency of this method (1). Fig. 1 Strategy for on-resin convergent synthesis of N-linked high Mannose Oligosaccharide containing glycopeptides. Here this strategy for N-linked glycopeptide synthesis is demonstrated by the synthesis of a glycosylated form of peptide T (ASTTTNYT) containing the high Mannose Oligosaccharide Man8GlcNAc2, 1. Peptide T is a fragment of the HIV-1 envelope protein gp120 consisting of residues 185 to 192 which contains a naturally occurring N-linked glycosylation site consensus sequence (2–3).
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study of on resin convergent synthesis of n linked glycopeptides containing a large high Mannose n linked Oligosaccharide
Journal of the American Chemical Society, 2010Co-Authors: Rui Chen, Thomas J TolbertAbstract:Here we present a convergent on-resin glycosylamine coupling strategy for solid phase N-linked glycopeptide synthesis, and apply it to the synthesis of high Mannose containing glycopeptides. In this strategy, the 2-phenylisopropyl protecting group is used as an orthogonal handle to create glycosylation sites on-resin after synthesis of nonglycosylated peptides. In addition to allowing selective deprotection of aspartic acid residues for creation of glycosylation sites, the 2-phenylisopropyl protecting group also efficiently suppresses aspartimide formation during peptide synthesis. The key step of on-resin glycosylamine coupling to an aspartic acid residue was first optimized for a small sugar, N-acetylglucosamine, and then applied to a much larger high Mannose Oligosaccharide, Man8GlcNAc2. Satisfying coupling yields were obtained for both small and large sugars. The use of on-resin glycosylamine coupling simplifies purification of N-linked glycopeptides, and also allows convenient recovery of unreacted v...
Uwe P. Weitzel - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of photolabile mono- and di-valent α-d-mannoside-6-phosphates as chemically modifying probes for Mannose-6-phosphate-receptors
Carbohydrate Research, 1995Co-Authors: Jochen Lehmann, Frank Schweizer, Uwe P. WeitzelAbstract:Abstract Two photoaffinity probes, disodium 3′-azibutyl α- d -mannopyranoside-6-phosphate and tetrasodium 2-azi-1,10-bis(α- d -mannopyranosyloxy-6-phosphate)decane were synthesized for the regioselective chemical modification of Mannose-6-phosphate receptors. Disodium 3′-azibutyl α- d -mannopyranoside-6-phosphate was obtained by chemical α-mannosylation of 3-azibutanol and subsequent 6-phosphorylation of the mannosyl residue. The corresponding divalent ligand, mimicking a high Mannose Oligosaccharide with two Mannose-6-phosphate end groups, was obtained by the same procedure but with 2-azi-1,10-decanediol as the aglyconic alcohol. In preliminary experiments, both photolabile ligands had affinity to cation-independent Mannose-6-phosphate receptors from bovine testes.
Javier Ramos-soriano - One of the best experts on this subject based on the ideXlab platform.
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Straightforward synthesis of Man9, the relevant epitope of the high-Mannose Oligosaccharide.
Organic & biomolecular chemistry, 2017Co-Authors: Javier Ramos-soriano, M. Carmen De La Fuente, Noelia De La Cruz, Rute Cunha Figueiredo, Javier Rojo, José J. ReinaAbstract:The high-Mannose Oligosaccharide (or its corresponding Man9 epitope) is the most abundant structure present in pathogen envelope glycoproteins. These glycans play a key role in the pathogenesis of several pathogens and also in the communication with the immune system. Understanding the mechanism of action of these glycans requires the access to pure and chemically well-defined structures in reasonable amounts. The synthesis of these complex branched Oligosaccharides is not trivial and few syntheses are reported in the literature with several synthetic and purification steps and low overall yields. In this work, we described a very efficient synthetic alternative to access this relevant Man9 epitope in a very straightforward manner.