Kevin Downard is a British - Australian academic scientist whose research specialises in the improving responses to infectious disease through the application and development of mass spectrometry and other molecular approaches in the life and medical sciences. Downard has over 35 years of experience in the field and has written 150 lead-author scientific peer-reviewed journal publications, and two books including a textbook [1] for the Royal Society of Chemistry and the first book to be published on the role of mass spectrometry in the study of protein interactions. [2]
Downard was awarded his Ph.D. degree from the University of Adelaide in South Australia where he received the inaugural Donald Stranks fellowship.
A major focus of his research is to arrest the impact of infectious disease causing viruses. For some 25 years, he has led the development of new mass spectrometry, bioinformatics and computer-aided approaches to characterise respiratory viruses and is an international leader in this field. He has developed approaches to type, subtype, [3] study the lineage, antigenicity, [4] and evolution [5] [6] of the influenza virus [7] and other respiratory biopathogens, [8] including SARS CoV-2, [9] [10] [11] and has identified and investigated the molecular basis of new antiviral enzyme inhibitors, to help arrest the impact of infectious diseases on human health. [12] His laboratory has led Australia's response to the SARS-CoV2 virus with mass spectrometry since 2020.
Downard held a post-doctoral fellowship from 1991 at the Massachusetts Institute of Technology (MIT) to advance protein sequencing by tandem mass spectrometry. He led the laboratory's early implementation of electrospray ionization (ESI) on a high end, four sector mass spectrometer and investigated subtleties of tandem mass spectra to help advance this application [13] He remained at MIT as the Assistant Director of the former National Institutes of Health Mass Spectrometry Research Resource at MIT before leading his own research laboratories in the United States and Australia over the past 25 years. During this time, he has developed new proteotyping approaches to study viruses, viral proteins, [14] and protein structures and interactions more generally to advance the application of MS in biology and medicine. [15] In recent years, he has developed a new mass (i.e. numbers) based molecular phylogenetics approach (referred to as "phylonumerics") that avoids the need for sequence data or sequence alignments [16] and has been applied to a range of evolutionary biology applications. [17]
His laboratory was the first to demonstrate the preservation (in 1999) [18] of large macromolecular complexes on conventional Matrix-assisted laser desorption/ionization (MALDI) targets for their indirect detection, later referred to as Intensity fading MALDI mass spectrometry by others. [19] He also co-developed protein footprinting experiments, in the same year, employing radicals to study protein structures and was the first to apply the technique to study protein complexes. [20]
Downard has been internationally recognised for his research having received awards from both American (ASMS 1999) and British (2016) mass spectrometry societies. He has received four international fellowships from the Australian Academy of Science and the Japan Society for the Promotion of Science. He convened and chaired the second Sir Mark Oliphant Conference on Proteomics in 2003 and the largest biennial Australian mass spectrometry conference in 2009 [21] after serving on the Executive MS Committee for 7 years (2002-2005 & 2007-2009). He has been active in promoting the importance of research in his field and the history of mass spectrometry and its pioneers [22] [23] for which he received the Moran award from the Australian Academy of Science in 2006. His activities have been highlighted in scientific journals in the analytical sciences, scientific web resources, and in the media including interviews with the Australian Broadcasting Corporation (ABC Australia). He has served on a range of national science, expert panel and professional society committees. He held the role of Biotechnology Program Director for almost a decade and was a founding executive member and advisor to the Sydney Emerging Infectious Disease and Biosecurity Institute. He has collaborated with a range of industry partners in the biotechnology and analytical science sector.
A glycome is the entire complement or complete set of all sugars, whether free or chemically bound in more complex molecules, of an organism. An alternative definition is the entirety of carbohydrates in a cell. The glycome may in fact be one of the most complex entities in nature. "Glycomics, analogous to genomics and proteomics, is the systematic study of all glycan structures of a given cell type or organism" and is a subset of glycobiology.
Tandem mass spectrometry, also known as MS/MS or MS2, is a technique in instrumental analysis where two or more stages of analysis using one or more mass analyzer are performed with an additional reaction step in between these analyses to increase their abilities to analyse chemical samples. A common use of tandem MS is the analysis of biomolecules, such as proteins and peptides.
Peptide mass fingerprinting (PMF), also known as protein fingerprinting, is an analytical technique for protein identification in which the unknown protein of interest is first cleaved into smaller peptides, whose absolute masses can be accurately measured with a mass spectrometer such as MALDI-TOF or ESI-TOF. The method was developed in 1993 by several groups independently. The peptide masses are compared to either a database containing known protein sequences or even the genome. This is achieved by using computer programs that translate the known genome of the organism into proteins, then theoretically cut the proteins into peptides, and calculate the absolute masses of the peptides from each protein. They then compare the masses of the peptides of the unknown protein to the theoretical peptide masses of each protein encoded in the genome. The results are statistically analyzed to find the best match.
In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy-absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules and various organic molecules, which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multi-charged ions.
Surface-enhanced laser desorption/ionization (SELDI) is a soft ionization method in mass spectrometry (MS) used for the analysis of protein mixtures. It is a variation of matrix-assisted laser desorption/ionization (MALDI). In MALDI, the sample is mixed with a matrix material and applied to a metal plate before irradiation by a laser, whereas in SELDI, proteins of interest in a sample become bound to a surface before MS analysis. The sample surface is a key component in the purification, desorption, and ionization of the sample. SELDI is typically used with time-of-flight (TOF) mass spectrometers and is used to detect proteins in tissue samples, blood, urine, or other clinical samples, however, SELDI technology can potentially be used in any application by simply modifying the sample surface.
Soft laser desorption (SLD) is laser desorption of large molecules that results in ionization without fragmentation. "Soft" in the context of ion formation means forming ions without breaking chemical bonds. "Hard" ionization is the formation of ions with the breaking of bonds and the formation of fragment ions.
MALDI mass spectrometry imaging (MALDI-MSI) is the use of matrix-assisted laser desorption ionization as a mass spectrometry imaging technique in which the sample, often a thin tissue section, is moved in two dimensions while the mass spectrum is recorded. Advantages, like measuring the distribution of a large amount of analytes at one time without destroying the sample, make it a useful method in tissue-based study.
Protein mass spectrometry refers to the application of mass spectrometry to the study of proteins. Mass spectrometry is an important method for the accurate mass determination and characterization of proteins, and a variety of methods and instrumentations have been developed for its many uses. Its applications include the identification of proteins and their post-translational modifications, the elucidation of protein complexes, their subunits and functional interactions, as well as the global measurement of proteins in proteomics. It can also be used to localize proteins to the various organelles, and determine the interactions between different proteins as well as with membrane lipids.
Top-down proteomics is a method of protein identification that either uses an ion trapping mass spectrometer to store an isolated protein ion for mass measurement and tandem mass spectrometry (MS/MS) analysis or other protein purification methods such as two-dimensional gel electrophoresis in conjunction with MS/MS. Top-down proteomics is capable of identifying and quantitating unique proteoforms through the analysis of intact proteins. The name is derived from the similar approach to DNA sequencing. During mass spectrometry intact proteins are typically ionized by electrospray ionization and trapped in a Fourier transform ion cyclotron resonance, quadrupole ion trap or Orbitrap mass spectrometer. Fragmentation for tandem mass spectrometry is accomplished by electron-capture dissociation or electron-transfer dissociation. Effective fractionation is critical for sample handling before mass-spectrometry-based proteomics. Proteome analysis routinely involves digesting intact proteins followed by inferred protein identification using mass spectrometry (MS). Top-down MS (non-gel) proteomics interrogates protein structure through measurement of an intact mass followed by direct ion dissociation in the gas phase.
Bottom-up proteomics is a common method to identify proteins and characterize their amino acid sequences and post-translational modifications by proteolytic digestion of proteins prior to analysis by mass spectrometry. The major alternative workflow used in proteomics is called top-down proteomics where intact proteins are purified prior to digestion and/or fragmentation either within the mass spectrometer or by 2D electrophoresis. Essentially, bottom-up proteomics is a relatively simple and reliable means of determining the protein make-up of a given sample of cells, tissues, etc.
Laser spray ionization refers to one of several methods for creating ions using a laser interacting with a spray of neutral particles or ablating material to create a plume of charged particles. The ions thus formed can be separated by m/z with mass spectrometry. Laser spray is one of several ion sources that can be coupled with liquid chromatography-mass spectrometry for the detection of larger molecules.
Capillary electrophoresis–mass spectrometry (CE–MS) is an analytical chemistry technique formed by the combination of the liquid separation process of capillary electrophoresis with mass spectrometry. CE–MS combines advantages of both CE and MS to provide high separation efficiency and molecular mass information in a single analysis. It has high resolving power and sensitivity, requires minimal volume and can analyze at high speed. Ions are typically formed by electrospray ionization, but they can also be formed by matrix-assisted laser desorption/ionization or other ionization techniques. It has applications in basic research in proteomics and quantitative analysis of biomolecules as well as in clinical medicine. Since its introduction in 1987, new developments and applications have made CE-MS a powerful separation and identification technique. Use of CE–MS has increased for protein and peptides analysis and other biomolecules. However, the development of online CE–MS is not without challenges. Understanding of CE, the interface setup, ionization technique and mass detection system is important to tackle problems while coupling capillary electrophoresis to mass spectrometry.
Protein footprinting is a term used to refer to a method of biochemical analysis that investigates protein structure, assembly, and interactions within a larger macromolecular assembly. It was originally coined in reference to the use of limited proteolysis to investigate contact sites within a monoclonal antibody - protein antigen complex and a year later to examine the protection from hydroxyl radical cleavage conferred by a protein bound to DNA within a DNA-protein complex. In DNA footprinting the protein is envisioned to make an imprint at a particular point of interaction. This latter method was adapted through the direct treatment of proteins and their complexes with hydroxyl radicals and can be generally denoted RP-MS akin to the designation used for Hydrogen-deuterium exchange Mass Spectrometry.
Franz Hillenkamp was a German scientist known for his development of the laser microprobe mass analyzer and, with Michael Karas, matrix-assisted laser desorption/ionization (MALDI).
Desorption/ionization on silicon (DIOS) is a soft laser desorption method used to generate gas-phase ions for mass spectrometry analysis. DIOS is considered the first surface-based surface-assisted laser desorption/ionization (SALDI-MS) approach. Prior approaches were accomplished using nanoparticles in a matrix of glycerol, while DIOS is a matrix-free technique in which a sample is deposited on a nanostructured surface and the sample desorbed directly from the nanostructured surface through the adsorption of laser light energy. DIOS has been used to analyze organic molecules, metabolites, biomolecules and peptides, and, ultimately, to image tissues and cells.
Intensity-fading MALDI is a term coined to rename an existing method originally reported in 1999 to indirectly study a Protein–protein interaction or other protein complex and the same year applied to a biological mixture to study the antigenicity of the influenza virus. It involves treating a protein and a potential binding partner with a site-specific endoproteinase with the binding sites identified by their reduced area in a MALDI mass spectrum compared to that of non-bound protein control. It was falsely reported as new and novel in a later application by a Spanish group. The true origins of the approach and a range of applications including those employing gel based separations, drug-protein interactions and the relative affinity of such interactions, are described in a review article.
Peter Nemes is a Hungarian-American chemist, who is active in the fields of bioanalytical chemistry, mass spectrometry, cell/developmental biology, neuroscience, and biochemistry.
Ron M.A. Heeren is a Dutch scientist in mass spectrometry imaging. He is currently a distinguished professor at Maastricht University and the scientific director of the Multimodal Molecular Imaging Institute (M4I), where he heads the division of Imaging Mass Spectrometry.
Richard M. Caprioli is an American chemist known for his contributions to mass spectrometry imaging.