New Fairlie Group paper: Europium-Labeled Synthetic C3a Protein as a Novel Fluorescent Probe for Human Complement C3a Receptor

Europium-Labeled Synthetic C3a Protein as a Novel Fluorescent Probe for Human Complement C3a Receptor

Dantas de Araujo A, Wu C, Wu KC, Reid RC, Durek T, Lim J, Fairlie DP.


Measuring ligand affinity for a G protein-coupled receptor is often a crucial step in drug discovery. It has been traditionally determined by binding putative new ligands in competition with native ligand labeled with a radioisotope of finite lifetime. Competing instead with a lanthanide-based fluorescent ligand is more attractive due to greater longevity, stability, and safety. Here, we have chemically synthesized the 77 residue human C3a protein and conjugated its N-terminus to europium diethylenetriaminepentaacetate to produce a novel fluorescent protein (Eu–DTPA–hC3a). Time-resolved fluorescence analysis has demonstrated that Eu–DTPA–hC3a binds selectively to its cognate G protein-coupled receptor C3aR with full agonist activity and similar potency and selectivity as native C3a in inducing calcium mobilization and phosphorylation of extracellular signal-regulated kinases in HEK293 cells that stably expressed C3aR. Time-resolved fluorescence analysis for saturation and competitive binding gave a dissociation constant (Kd) of 8.7 ± 1.4 nM for Eu–DTPA–hC3a and binding affinities for hC3a (pKi of 8.6 ± 0.2 and Ki of 2.5 nM) and C3aR ligands TR16 (pKi of 6.8 ± 0.1 and Ki of 138 nM), BR103 (pKi of 6.7 ± 0.1 and Ki of 185 nM), BR111 (pKi of 6.3 ± 0.2 and Ki of 544 nM) and SB290157 (pKi of 6.3 ± 0.1 and Ki of 517 nM) via displacement of Eu–DTPA–hC3a from hC3aR. The macromolecular conjugate Eu–DTPA–hC3a is a novel nonradioactive probe suitable for studying ligand–C3aR interactions with potential value in accelerating drug development for human C3aR in physiology and disease.

Bioconjug Chem. 2017, In Press.

May 31. doi: 10.1021/acs.bioconjchem.7b00132.

New Fairlie Group Paper: Quinazolinone derivatives as inhibitors of homologous recombinase RAD51.

Quinazolinone derivatives as inhibitors of homologous recombinase RAD51.

Ward A, Dong L, Harris JM, Khanna KK, Al-Ejeh F, Fairlie DP, Wiegmans AP, Liu L.


Bioorg Med Chem Lett. 2017, In Press.

May 15. pii: S0960-894X(17)30520-6. doi: 10.1016/j.bmcl.2017.05.039.


RAD51 is a vital component of the homologous recombination DNA repair pathway and is overexpressed in drug-resistant cancers, including aggressive triple negative breast cancer (TNBC). A proposed strategy for improving therapeutic outcomes for patients is through small molecule inhibition of RAD51, thereby sensitizing tumor cells to DNA damaging irradiation and/or chemotherapy. Here we report structure-activity relationships for a library of quinazolinone derivatives. A novel RAD51 inhibitor (17) displays up to 15-fold enhanced inhibition of cell growth in a panel of TNBC cell lines compared to compound B02, and approximately 2-fold increased inhibition of irradiation-induced RAD51 foci formation. Additionally, compound 17 significantly inhibits TNBC cell sensitivity to DNA damage, implying a potentially targeted therapy for cancer treatment.

New review from the Fairlie Group out now in Chemical Reviews. Orally absorbed cyclic peptides.

Orally Absorbed Cyclic Peptides

Nielsen DS, Shepherd NE, Xu W, Lucke AJ, Stoermer MJ and Fairlie DP.

Chem. Rev., In Press
Publication Date (Web): May 25, 2017

Peptides and proteins are important mediators of biological processes, and modulating protein-target interactions is an attractive way to develop new drugs. Unfortunately proteins and peptides are usually only deliverable intravenously, due to their generally poor absorption, or rapid degradation when take orally.

Due to their high specificity however, increasing efforts are being made to modify peptides to increase their oral absorption and consequently, their utility. One approach used by nature and synthetic chemists alike is to increase the stability of peptidic drug candidates by cyclisation.

In this review we survey 125 cyclic peptides and analyse how cyclisation and other modifications affects the flexibility and other molecular properties such as the rule-of-five (RO5) rubric, more commonly associated with small molecule drugs.


Xray crystal structure of cyclosporine A, Dotted lines indicate internal hydrogen bonds. (Loosli 1985).



Xray crystal structure of cyclic hexaleucine , a small bioavailable cyclic peptide. (Hill 2014)

This work was supported by grants from the National Health and Medical Research Council and the Australian Research Council


Orally absorbed cyclic peptides. Daniel S. Nielsen, Nicholas E. Shepherd, Weijun Xu, Andrew J. Lucke, Martin J. Stoermer,* and David P. Fairlie* Chem. Rev., 2017, Article ASAP. Copyright (2017) American Chemical Society. DOI: 10.1021/acs.chemrev.6b00838. TOC graphic reprinted with permission.

The conformation of cyclosporin a in the crystal and in solution.Loosli, H.-R.; Kessler, H.; Oschkinat, H.; Weber, H.-P.; Petcher, T.J.; Widmer, A. Peptide conformations. Part 31†. Helv. Chim. Acta 1985, 68, 682-704. DOI: 10.1002/hlca.19850680319

Cyclic Penta- and Hexa- Leucine Peptides Without N-Methylation Are Orally Absorbed. Timothy A Hill , Rink-Jan J Lohman , Huy Ngoc Hoang , Daniel S Nielsen , Conor CG Scully, Woan Mei Kok , Ligong Liu , Andrew J Lucke , Martin J Stoermer , Christina I Schroeder , Stephanie Chaousis , Barbara Colless , Paul Vincent Bernhardt , David J. Edmonds , David A. Griffith , Charles J. Rotter , Roger B. Ruggeri , David A. Price , Spiros Liras , David J Craik , and David P. Fairlie, ACS Med. Chem. Lett., 2014, 5, 1148-1151. Copyright (2014) American Chemical Society. DOI: 10.1021/ml5002823. TOC graphic reprinted with permission.

Drugs and Drug-Like Molecules Activate or Inhibit T cells

7 February, 2017

PhD student Weijun Xu from The University of Queensland’s Institute for Molecular Bioscience used computer modelling to predict chemical structures, drugs and drug-like molecules that activate or inhibit T cells called MAIT cells. Such small compounds included salicylates, non-steroidal anti-inflammatory drugs like diclofenac, and drug metabolites. Researchers from University of Queensland, Monash University and University of Melbourne are a step closer to understanding immune sensitivities to well-known, and commonly prescribed, medications (Nature Immunology 2017, doi: 10.1038/ni.3679 [Epub ahead of print]).

New Fairlie Group C3aR, C5aR and obesity paper out in press

C5aR and C3aR antagonists each inhibit diet-induced obesity, metabolic dysfunction, and adipocyte and macrophage signaling.

Lim J, Iyer A, Suen JY, Seow V, Reid RC, Brown L, Fairlie DP.

FASEB J. 2012 Nov 1. [Epub ahead of print]

PMID: 23118029

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