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ABSTRACT: Self-adjuvanting tricomponent vaccines were prepared and assessed for their self-assembly and immunological activity in mouse models. The vaccines each consisted of a peptide or glycopeptide antigen that corresponds to a complete copy of the variable-number tandem repeat (VNTR) of the tumor-associated mucin 1 (MUC1) glycoprotein, the universal T-cell helper peptide epitope PADRE, and the immunoadjuvant Pam(3) CysSer. The vaccines were shown to spontaneously self-assemble in water to form isotropic particles varying in size from 17 to 25 nm and elicited robust humoral responses in murine models without the addition of an external adjuvant. The serum antibodies could recognize tumor-associated MUC1 epitopes on the surface of MCF7 breast-cancer cells and B16 melanoma cells, which overexpress this tumor-associated glycoprotein.
Chemistry 10/2012; · 5.93 Impact Factor
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ABSTRACT: The synthesis of sublancin 168, a unique S-glucosylated bacteriocin antibiotic, is described. The natural product and two S-glycosylated variants were successfully prepared via native chemical ligation followed by folding. The synthetic glycopeptides were shown to possess primarily an α-helical secondary structure by CD and NMR studies.
Organic Letters 04/2012; 14(7):1910-3. · 5.86 Impact Factor
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ABSTRACT: Don't freeze! A native chemical ligation-desulfurization strategy has been employed for the convergent synthesis of a library of defined antifreeze glycopeptides and glycoproteins (AFGPs) ranging in size from 1.2 to 19.5 kDa. These AFGPs possessed the secondary structure of a polyproline type II helix and exhibited significant ice recrystallization inhibition and thermal hysteresis activity.
Angewandte Chemie International Edition 03/2012; 51(15):3606-10. · 13.45 Impact Factor
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ABSTRACT: Site-specific characterisation of mucin-type O-linked glycosylation is an analytical challenge due to glycan heterogeneity, lack of glycosylation site consensus sequence and high density of occupied glycosylation sites. Here, we report the use of electron transfer dissociation (ETD) for the site-specific characterisation of densely glycosylated mucin-type O-linked glycopeptides using ESI-IT-MS/MS. Synthetic glycopeptides from the human mucin-1 (MUC-1) tandem repeat region containing a range of O-linked, tumour-associated carbohydrate antigens, namely Tn, T and sialyl T, with different glycosylation site occupancies and an increasing number of tandem repeats were studied. In addition, a glycopeptide from the anti-freeze glycoprotein of Antarctic and Arctic notothenoids, bearing four O-linked, per-acetylated T antigens was characterised. ETD MS/MS of infused or capillary LC-separated glycopeptides provided broad peptide sequence coverage (c/z·-type fragment ions) with intact glycans still attached to the Ser/Thr residues. Thus, the glycosylation sites were unambiguously determined, while simultaneously obtaining information about the attached glycan mass and peptide identity. Highly sialylated O-glycopeptides showed less efficient peptide fragmentation, but some sequence and glycosylation site information was still obtained. This study demonstrates the capabilities of ETD MS/MS for site-specific characterisation of mucin-type glycopeptides containing high-density O-linked glycan clusters, using accessible and relative low-resolution/low-mass accuracy IT MS instrumentation.
Electrophoresis 12/2011; 32(24):3536-45. · 3.30 Impact Factor
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ABSTRACT: Synthesis of sulfated and unsulfated (glyco)peptide fragments of Hirudin P6 (a potent anticoagulant from the leech Hirudinaria manillensis) is described. The effect of O-glycosylation and tyrosine sulfation on thrombin binding and peptidolytic activity was investigated, together with the inhibition of fibrinogen cleavage.
Chemical Communications 11/2011; 48(10):1547-9. · 6.17 Impact Factor
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Angewandte Chemie International Edition 02/2011; 50(7):1635-9. · 13.45 Impact Factor
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ABSTRACT: MUC1 is a cell-surface, epithelial glycoprotein that forms an essential protective barrier of cells and serves to modulate intercellular communication. During cancer progression, the dysregulation of glycosyltransferases, which serve to elongate cell-surface glycans, leads to aberrant gIycosylation patterns on this glycoprotein. This results in the presentation of well-characterized, tumor-associated carbohydrate antigens (TACAs) which represent important biomarkers for a range of epithelial cancers. The synthesis of well-defined, multivalent MUC1 glycopeptide constructs bearing TACAs therefore represents a viable opportunity for the development of cancer vaccine candidates. We report herein the synthesis of a glycopeptide thioester, comprising the full eicosapeptide variable number tandem repeat (VNTR) region of MUC1, which was prepared bearing multiple copies of the cancer-associated TN antigen. The glycopeptide thioester was prepared on the solid-phase using two different methods on 2-chlorotrityl chloride and sulfamylbutyryl resins. The solid-phase assembly on 2-chlorotrityl chloride resin, followed by thioesterification in solution, afforded the desired thioester in 4% yield over 41 linear steps. Likewise, the glycopeptide thioester was successfully prepared on sulfamylbutyryl resin using an activation and thiol-release strategy in a 9% isolated yield. The resulting peptide thioester was successfully ligated to a deprotected MUC1 glycopeptide using the direct aminolysis ligation to afford a 5.8 kDa, 40 amino acid MUC1 glycopeptide bearing 10 copies of the T(N) antigen. This work represents an important step toward the immunological evaluation of multivalent MUC1 constructs.
Biopolymers 01/2011; 96(2):137-46. · 2.87 Impact Factor
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ABSTRACT: An efficient method for the convergent assembly of MUC1-lipopeptide vaccine candidates is described. Chimeras consisting of MUC1 glycopeptides (bearing multiple copies of the T(N) and T tumour-associated carbohydrate antigens) tethered to the lipopeptide immunoadjuvant Pam(3)CysSer were synthesised in high yields using a fragment-based condensation strategy.
Chemical Communications 09/2010; 46(34):6249-51. · 6.17 Impact Factor
