CMSDG Seminar of Oct 2021 Sign up now

Speaker: Joseph A. Loo, Phd  (Chemistry, UCLA)

Title: Illuminating the Dark Matter of Top-Down Mass Spectrometry

Location: Virtual meeting

Time: 12pm, Oct 19, 2021


Native mass spectrometry (MS) of proteins and protein assemblies reveals size and binding stoichiometry. But elucidating their structures to understand their function is more challenging. We show that native MS and native top-down MS, i.e., fragmentation of the gas-phase protein, can be effective for deriving structural information for soluble and membrane protein complexes, and much of this information can be correlated to the solution-phase structure. However, much more information (I believe) on protein structure can be derived if every peak in a tandem mass spectrum can be assigned – but why is this difficult? Non-MS experts would be surprised to learn that well over 50% of the peaks in a protein tandem mass spectrum are not assigned, and thus not used, i.e., ignored. What analytical method allows 50% of data to be thrown away? A few examples will be shown to demonstrate that attempting to assign every peak in a tandem mass spectrum could lead to new information related to a protein’s structure.


Joseph A. Loo is a Professor in the Department of Chemistry & Biochemistry and the Department of Biological Chemistry, David Geffen School of Medicine at the University of California, Los Angeles (UCLA). He is also a member of UCLA/DOE Institute for Genomics and Proteomics and the UCLA Molecular Biology Institute. His research interests include analytical chemistry, the mass spectrometry characterization of peptides and proteins and post-translational modifications, and their application for proteomics and disease biomarkers. He is the author of over 335 scientific publications. He is the 2021 recipient of the Eastern Analytical Symposium (EAS) Award for Outstanding Achievement in Mass Spectrometry.

He is on the Editorial Boards of several scientific journals, and currently he is the Editor-in-Chief for the Journal of the American Society for Mass Spectrometry. He has held leadership and advisory positions with scientific organizations, including membership on the Board of Directors for the American Society for Mass Spectrometry (ASMS) and the US Human Proteome Organization (US HUPO). Before he joined UCLA in 2001, he was an Associate Research Fellow and Group Leader of the Biological Mass Spectrometry and Proteomics Teams at Parke-Davis Pharmaceutical (that later became Pfizer Global Research), Ann Arbor, MI.

He received his Ph.D. in analytical chemistry from Cornell University with Professor Fred W. McLafferty, where he worked on the development of high resolution mass spectrometry for bioanalytical applications. He carried out research as a post-doctoral fellow, and later as a Senior Scientist, at Pacific Northwest National Laboratory (Richland, WA) with Dr. Richard Smith on the development of electrospray ionization mass spectrometry and capillary electrophoresis for protein characterization.