Geoffrey M. Williams

Direct peptide lipidation through thiol-ene coupling enables rapid synthesis and evaluation of self-adjuvanting vaccine candidates.

A radical lipidation: Application of a novel thiol-ene lipidation enables the one-step synthesis of self-adjuvanting antigenic peptides as vaccine candidates. The resultant monoacyl lipopeptides are shown to activate monocytes in a robust manner.

The Synthesis of Phosphopeptides Using Microwave-assisted Solid Phase Peptide Synthesis

A series of phosphorylated peptides were synthesised using microwave mediated solid phase peptide synthesis. Acidic cleavage of peptides from the solid support using microwave irradiation often resulted in reattachment of the phosphate benzyl protecting group to the peptide chain. However for most phosphopeptide sequences performing the cleavage reaction at room temperature in order to minimize this undesired alkylation was successful. Notably for phosphopeptides containing a methionine residue flanking the phosphorylated residue (for serine and threonine) the trifluoroacetic acid mediated cleavage afforded the benzylated side product as a major component. This detrimental process was not observed for a corresponding tyrosine containing sequence.

Synthesis of a dicarba analogue of human β-defensin-1 using a combined ring closing metathesis--native chemical ligation strategy.

We herein describe the first synthesis of the native antimicrobial protein HBD-1 making use of an orthogonal thiol protection strategy and a novel dicarba analogue thereof. The robust hydrocarbon linkage was installed by replacement of one disulfide bond using on-resin ring closing metathesis. The unprecedented 59-membered C-terminal cysteine macrocyclic fragment thus formed then engages in native chemical ligation allowing convergent access to this unique synthetic protein analogue.

Synthesis of Neoglycopeptides via Click Chemistry

Novel chemical methods to access homogeneous samples of glycopeptides and glycoproteins and their mimetics, so-called neoglycopeptides and neoglycoproteins, have developed rapidly in recent years owing to an increased need to investigate both their roles in molecular biology and their potential as therapeutic agents. This article summarizes the application of the copper-catalyzed azide-alkyne cycloaddition for the chemical synthesis of neoglycopeptides and neoglycoproteins.

Identification of key residues involved in adrenomedullin binding to the AM1 receptor

Adrenomedullin (AM) is a peptide hormone whose receptors are members of the class B GPCR family. They comprise a heteromer between the GPCR, the calcitonin receptor‐like receptor and one of the receptor activity‐modifying proteins 1–3. AM plays a significant role in angiogenesis and its antagonist fragment AM22–52 can inhibit blood vessel and tumour growth. The mechanism by which AM interacts with its receptors is unknown.

Synthesis of glycosylated 5-hydroxylysine, an important amino acid present in collagen-like proteins such as adiponectin.

The synthesis of naturally occurring glycosylated (2S,5R)-hydroxylysine still remains a challenge. This perspective highlights the importance of this post-translationally modified amino acid residue in the observed bioactivity of collagen and related collagen-like proteins such as adiponectin, an important target for the treatment of type II diabetes. Strategies employed to date for the syntheses of (2S,5R)-hydroxylysine and the methods to effect glycosylation of this modified amino acid are also summarized herein.

An important side reaction using the thiol, 3,6-dioxa-1,8-octanedithiol (DODT), in 9-fluorenylmethoxycarbonyl-based solid phase peptide synthesis.

A considerable quantity of an alkylation by‐product is observed when using 3,6‐dioxa‐1,8‐octanedithiol as a scavenger during acidic release of peptides containing the thioether amino acid methionine from the solid support. Adjustment of the cleavage conditions by replacement of 3,6‐dioxa‐1,8‐octanedithiol with ethane dithiol or by using methionine sulfoxide as an alternative to methionine resulted in no such impurity. The by‐product was detectable by liquid chromatography and mass spectrometry and characterised by NMR spectroscopy of an isolated model peptide. It could be effectively removed in a separate post cleavage step by treatment with dilute aqueous acid at 37 °C. Copyright

Synthesis of a 6,6‐Spiroketal Amino Acid and Its Incorporation into a Peptide Turn Sequence Using Solid‐Phase Peptide Synthesis

Spiropins for SPPS: The rigid structure of an anomerically stabilised spiroketal motif enables the appendage of substituents in a fixed conformation. To assess the ability of a spiroketal motif to induce a turn structure and participate in solid-phase peptide synthesis (SPPS), an Fmoc-spiroketal amino acid was synthesised and incorporated into a spiroketal-containing cyclic peptide.

Synthesis of the IGF-II-like hormone vesiculin using regioselective formation of disulfide bonds

Diabetes mellitus, characterised by hyperglycemia and altered β-cell function, is an increasingly common disorder affecting millions of individuals world-wide. While therapeutic regimens exist to manage the condition, diabetic individuals remain prone to complications that are detrimental to both their length and quality of life. An improved understanding of the disease which may then enable development of new treatments is therefore a desirable goal. Vesiculin, a novel IGF-II-like protein was recently isolated from the secretory granules of murine β-cells, and preliminary studies indicate it is capable of signalling via the insulin receptor (IR)/insulin-like growth factor receptor 1(IGF1R) family giving it the potential to elicit both metabolic and mitogenic responses in the beta-cell. In order to facilitate further studies on this new member of the insulin-family of hormones, we undertook a chemical synthesis of the protein using regioselective disulfide bond formation.

Augmenting Influenza-Specific T Cell Memory Generation with a Natural Killer T Cell-Dependent Glycolipid–Peptide Vaccine

The development of a universal vaccine for influenza A virus (IAV) that does not require seasonal modification is a long-standing health goal, particularly in the context of the increasing threat of new global pandemics. Vaccines that specifically induce T cell responses are of considerable interest because they can target viral proteins that are more likely to be shared between different virus strains and subtypes and hence provide effective cross-reactive IAV immunity. From a practical perspective, such vaccines should induce T cell responses with long-lasting memory, while also being simple to manufacture and cost-effective. Here we describe the synthesis and evaluation of a vaccine platform based on solid phase peptide synthesis and bio-orthogonal conjugation methodologies. The chemical approach involves covalently attaching synthetic long peptides from a virus-associated protein to a powerful adjuvant molecule, α-galactosylceramide (α-GalCer). Strain-promoted azide-alkyne cycloaddition is used as a simple and efficient method for conjugation, and pseudoproline methodology is used to increase the efficiency of the peptide synthesis. α-GalCer is a glycolipid that stimulates NKT cells, a population of lymphoid-resident immune cells that can provide potent stimulatory signals to antigen-presenting cells engaged in driving proliferation and differentiation of peptide-specific T cells. When used in mice, the vaccine induced T cell responses that provided effective prophylactic protection against IAV infection, with the speed of viral clearance greater than that seen from previous viral exposure. These findings are significant because the vaccines are highly defined, quick to synthesize, and easily characterized and are therefore appropriate for large scale affordable manufacture.