The 4th International Peptide Symposium was held at the Cairns Convention Center in Far North Tropical Queensland, October 21–25, 2007. The meeting, which had the theme ‘Discovery to drugs: the peptide pipeline’ was organized by the Australian Peptide Association with Ian Smith and John Wade as the co-chairs. The meeting attracted over 420 delegates from all over the world, with large delegations from the Japanese, Korean, US and European peptide communities. As at previous Australian Peptide Symposia the meeting focused heavily on the role of emerging technologies in modern peptide and protein discovery, with a particular emphasis on proteomics and peptidomics. There were 74 oral and 212 poster presentations. Student poster prizes were awarded for each poster session. Specialist workshops were organized by ABI, Agilent, Thermo Scientific, Beckman Coulter and Bruker and there was an excellent trade display with 30 companies represented.
The meeting opened on the Sunday evening with a stimulating plenary lecture by Brian Chait (Rockefeller University, NY, USA) entitled Proteomic Approaches for Analyzing Complex Biological Machines. Brian presented a focused proteomics approach to dissect nuclear pore complexes. The role of cryolysis in avoiding damage to ribonucleoprotein complexes by released nucleases and proteases and redistribution of proteins was emphasized. Tagged proteins were then captured using magnetic beads and eluted proteins separated by SDS-PAGE prior to MS/MS analysis revealing 30 proteins associated with the complex. A spatial and temporal model was developed to envisage the biological machines generated by the protein complexes identified.
The remaining oral presentations were organized into individual morning sessions with parallel sessions running in the afternoons. Topics addressed were: protein misfolding and disease; peptidomimetics and drug design; new developments in peptide drug delivery; chemical peptide synthesis: innovations and applications; peptidomics: towards therapeutics; peptides-to-clinic; clinical proteomics; toxins and targets: new therapeutic and GMO leads; molecular interactions: exploring affinity and specificity; emerging technologies for studying peptide structure and function; new concepts in bioactive peptide design; peptidomics: biomarker analysis and characterization; peptide and protein engineering; peptides as drugs in infectious diseases and neuropeptides and pain. Space does not permit me to cover all the many excellent presentations that were made at the meeting. Instead I have tried to highlight some interesting technological applications that might be of particular interest to readers of this journal.
Peptidomics: towards therapeutics
William Hildebrand (University of Oklahoma Health Science Center, USA), likening Class 1 HLA molecules to an in vivo peptide scanning chip, presented his studies on the analysis of peptide epitopes unique to diseased cells to distinguish virus-affected and cancerous cells. Michael Przybylski (University of Konstanz, Germany) described new molecular approaches for immunotherapy and diagnosis of Alzheimer’s disease. Selective proteolytic epitope-excision and -extraction on the immobilized immune complexes, in combination with high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), were used as major methods for epitope identification. Christie Hunter (Applied Biosystems, Foster City, USA) described a protein biomarker research pipeline using a nonisobaric chemical labeling strategy with multiple reaction monitoring (MRM) for targeted multiplexed quantitation of biomarkers in plasma.
Peptides-to-clinic
Anna Maria Papini (University of Firenze, Italy) described an innovative ‘chemical reverse’ approach in which specific post-translational modifications (PTMs) are introduced during solid-phase synthesis to mimic conformational epitopes to fish out autoantibodies as disease biomarkers. Using this approach she was able to characterize N-glycosylation as one of the possible PTMs involved in multiple sclerosis.
Clinical proteomics
This session focused on many of the challenges involved in biomarker discovery and analysis. Ralph Bradshaw (University of California, San Francisco, USA) discussed the need to carefully characterize PTMs and illustrated his talk with a number of examples of situations where extreme care must be taken to ensure correct identification (e.g., formylation versus dimethylation; double oxidation versus persulfide formation; sulfation versus phosphorylation). He also discussed the problem of distinguishing artifactual modifications from those genuinely occurring in vivo. Bill Hancock (Northeastern University, MA, USA) discussed the use of multiple-lectin affinity chromatography as part of a multidimensional separation approach to mine deeper into the plasma glycoproteome. The group at the Ludwig Institute (Melbourne, Australia) discussed the potential of using proteomics to identify tumor-related products in fecal samples from colon cancer patients. Alan Sawyer (Monash University, Australia) described the automated high throughput hybridoma platform that is being set up, which promises to generate panels of monoclonal antibodies raised against 5000 novel antigenic targets per annum. In particular they plan to produce monoclonal antibodies against phosphospecific antibodies raised against phosphopeptides of all the phosphorylation states of all the human kinases and selected substrates for use in protein microarray and other multiplex screens.
Molecular interactions: exploring affinity & specificity
This session included a number of presentations on alternative technologies for detecting and analyzing protein–protein interactions. Bill Gelb (MicroCal LLC, Northampton, MA, USA) gave an excellent overview of modern microcalorimetric techniques. Gideon Schreiber (Weizmann Institute, Israel) described their recent studies on mutation analysis to analyze the interface of a number of different protein complexes. These studies were performed on the recently released Biorad ProteOn high-throughput SPRi system that uses image analysis to simultaneously track optical changes at many different sites in an image (array) with high sensitivity, without the need for molecular labeling, and enables simultaneous measurements on a 6 × 6 grid laid down on the sensor surface. Patrick Schaeffer (James Cook University, Queensland, Australia) presented their data on protein–DNA interactions involved in the termination of DNA replication using the BIAcore. These data suggest that a ‘molecular mousetrap’ is set by the binding of the Tus terminator protein with Ter DNA sites, which is sprung by strand separation by the DnaB helicase. They discussed the potential application of the extraordinary stable Tus–Ter lock in the area of proteomics for protein and DNA display on chip surfaces and diagnostics. In the same session Stefan Stahl (Royal Institute of Technology, Stockholm, Sweden) described the use of affibody molecules for tumor targeting applications. The clinical use of a high-affinity anti-Her2 affibody was presented. Interestingly it was shown that this could still bind in vivo when patients were being treated with the anti-Her2 antibody, Herceptin®. Malcolm Buckle (CNRS, Cachan, France) in the related poster session showed examples of another new optical biosensor system (GenOptics SPRi). This is also a multiplexed system in which a large number of surfaces (up to 400) can be laid down on a sensor surface and, like the Bio-Rad ProteOn, detected by charge-coupled device (CCD) cameras as a change in percentage reflectivity as molecules bind to the surface target. Malcolm also presented data on the development of novel Teflon® surfaces with low nonspecific binding.
Emerging technologies for studying peptide structure & function
Francis Separovic (University of Melbourne, Australia) presented her data on membrane interactions on antimicrobial peptides from Australian tree frogs. Correlation of solid-state NMR results with fluorescence, quartz crystal microbalance (QCM) and atomic force microscopy (AFM) data supported a transmembrane orientation and pore formation for longer peptides (21 and 25 residues) and a detergent-like mechanism for the shorter peptides (13 and 16 residues) in mixed phospholipid bilayers. John Lee (Monash University, Australia) also presented data on geometrical changes of antimicrobial peptides in neutral dimyristoylphosphatidylcholine (DMPC) and negatively charged (DMPC/dimyristoylphosphatidylglycine [DMPG]) membranes. In these studies surface plasmon resonance (BIAcore), dual polarization interferometry (Farfield) and AFM were used.
Peptidomics: biomarker analysis & characterization
Hidehito Mukai (Mitsubishi Kagaku Institute of Life Sciences, Tokyo, Japan) described their work on cryptides: functional peptides hidden within protein sequences. They had noted that some cryptides induced neutrophil function by direct activation of G proteins. These peptides had features in common in terms of positively charged and hydrophobic amino acids, but homologies in their primary structures were not apparent. Cryptide sequences with potential to activate G proteins based on the distribution of their charged and hydrophobic residues were identified using a bioinformatics approach. More than 20 cryptides were identified that activated neutrophils at submicromolar concentrations. Tony Purcell (Bio 21 Institute, Melbourne, Australia) reported on an immunopeptidomic approach to identify new targets in autoimmune disease. He observed T cell responses that are disease specific in patients with type 1 diabetes and rheumatoid arthritis. Peter Hoffman (University of Adelaide, Australia) presented data on immobilized metal ion affinity chromatography (IMAC), octyl (C8) and antibody-enriched magnetic beads for biomarker discovery: data were presented on a comparison of serum and plasma from a mouse model of gastric cancer with those from normal mice. Rudi Grim (Agilent Technologies, Santa Clara, USA) discussed extensions of their integrated enrichment, separation and nanospray microfluidic HPLC chips including the use of a titanium oxide surface for on-chip phosphopeptide enrichment. Naoto Minamino focused on their peptidomic studies on C-terminal amidated peptides, a post-translational modification frequently observed in bioactive compounds using human medullary thyroid carcinoma transformed calcitonin-producing (TT) cells that actively produce amidated peptides. Two novel amidated peptides were identified: NERP-1 and 2. Mass spectrometric analysis of immunoprecipitates showed that these compounds are present in rat brain. Biological studies suggested that the NERPs are novel modulators in body fluid homeostasis.
Conclusions
As at previous meetings in this series the role of emerging technologies in peptide and protein research and modern drug discovery was well demonstrated. Whilst there has recently been some skepticism on the ability of proteomics to deliver, this meeting clearly showed that exciting results are now being generated in a number of important biological areas using this technology. Whilst I have highlighted presentations with a technological thrust, one must not forget the excellent presentations by many eminent scientists in the areas of peptide and protein engineering, drug delivery, bioactive peptide design and endocrinology. The friendly ambience of the meeting stimulated much discussion and cross fertilization of ideas between the participants that will surely lead to further exciting new developments in the future.
Financial & competing interests disclosure
Edouard Nice is the co-chair of the Australian Peptide Association and was on the organizing committee for the 7th Australian Peptide Symposium. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.