Michael L. Gross

​Professor of Chemistry and of Immunology and Internal Medicine (School of Medicine)
PhD, University of Minnesota
BA, St. John's University
research interests:
  • Analytical Chemistry
  • Biological Chemistry
  • Biophysical Chemistry
  • Mass Spectrometry-Based Protein Biochemistry and Biophysics
  • Protein Footprinting
  • Proteomics
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contact info:

mailing address:

  • CB 1134
  • ST. LOUIS, MO 63130-4899
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Professor Gross's main research goal is the development of biophysical methods that use mass spectrometry to understand proteins, their interfaces, solvent accessibility, affinities of binding, and their folding and unfolding.

With support from the NIH, we work with proteins of biomedical importance, often with collaborators at WU and beyond.

One approach for footprinting is to map proteins with reactions of OH radicals. We termed our version “fast photochemical oxidation of proteins” or FPOP whereby we “paint” certain surface-accessible amino-acid residues by reacting the protein in a flow tube (see figure below) with radicals generated from H2O2 by a pulsed KrF laser (248 nm). With appropriate scavengers, the reaction time is remarkably short (~ 1 μsec). Certain amino acids react with the radicals to become oxidized (depicted as turning from “green” to “yellow”—see figure below). FPOP is useful for determining protein-protein interfaces, affinities for tiny amounts of proteins in biophysics, drug discovery, and epitope mapping.  FPOP is being adopted by biotechnology companies for quality control of protein therapeutics and for determining sites of interaction between a protein therapeutic and its target protein.

A unique application of FPOP is to follow fast protein folding or unfolding.  An example is the refolding of the protein barstar.  The unfolded form of the protein in a flowing solution is rapidly heated by a laser pulse.  At various times on the microsecond level following its start to fold, a second laser generates OH radicals whose reactions track the folding. As shown in the figure below are five residues (H17, I5, L20, L24, and F74) whose labeling becomes less as they are involved in formation of a hydrophobic core that can be viewed as the nucleus for its folding.  Few other experimental approaches can bring this level of detail to this important question in biophysics.

Footprinting can use many other reactions, and we are developing and applying these reactions.  For example, we use labeling with NEM (N-ethylmaleimide) to follow changes in the local environment of Cys, GEE (glycyl ethyl ester) to monitor changes of Asp and Glu, and carbenes to complement OH radical labeling especially of amino acids that are relatively “silent” to reactions with •OH.

Hydrogen/deuterium exchange (HDX) is another focus where we develop new methods and use them in problem solving.  Examples are pulsed HDX for following aggregation of Aβ, the plaque-forming protein in Alzheimer’s disease, and pH-dependent HDX for monitoring protein conformational changes as pH decreases.  We also use an HDX titration to determine protein-ligand affinities, a method we term PLIMSTEX (Protein Ligand Interaction by Mass Spectrometry, Titration and H/D Exchange). The figure below shows the titration of fatty-acid-binding protein (structure on upper left) with the fatty-acid ligand, potassium oleate, to give a complex (on lower right) that now contains the fatty-acid anion. The y-axis data come from MS, and the solid line is computed from our model that gives the equilibrium constant for the protein-ligand interaction. We are interested in applying this idea to determining affinities for specific regions of proteins, which is difficult by other affinity measurements.

We also utilize native electrospray where near-native forms of a protein or a protein complex are introduced into a mass spectrometer.  We discovered that activating the entire complex (note the large m/z on the x axis) by electron-capture dissociation (ECD) causes flexible regions of the constituent proteins to fragment. Example below is of FMO protein—collaboration with Blankenship—that fragments in those regions that are deemed flexible by x-ray crystallography (i.e., have large b factors).  The right side of the spectrum shows data for the complex undergoing charge neutralization whereas the right side shows the fragments. We complement these measurements with ion mobility, to look more closely at the details of collisionally induced unfolding, and cross linking, to determine the topology of the complex.

Select Publications

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases Within the Bacteriophage T7 Replisome, Jamie R. Wallen, Hao Zhang, Caroline Weis, Weidong Cui, Brittni M. Foster, Chris M. W. Ho, Michal Hammel, John A. Tainer, Michael L. Gross, and Tom Ellenberger, Structure, 25, 157–166, (2017).  PMC5267931

Native Mass Spectrometry Characterizes the Photosynthetic Reaction Center Complex from the Purple Bacterium Rhodobacter sphaeroides, Hao Zhang, Lucas B. Harrington, Yue Lu, Mindy Prado, Rafael Saer, Don Rempel, Robert E. Blankenship, and Michael L. Gross, J. Amer. Soc. Mass Spectrom., 28, 87-95 (2017).  PMC5613939

Native Mass Spectrometry Analysis of Oligomerization States of Fluorescence Recovery Protein and Orange Carotenoid Protein: Two Proteins Involved in the Cyanobacterial Photoprotection Cycle, Yue Lu, Haijun Liu, Rafael G. Saer, Hao Zhang, Christine M. Meyer, Veronica L. Li, Liuqing Shi, Jeremy D. King, Michael L. Gross, and Robert E. Blankenship, Biochemistry, 56, 160-166 (2017).  PMC5369232

Incorporation of a Reporter Peptide in FPOP Compensates for Adventitious Scavengers and Permits Time-dependent Measurements, Ben Niu, Brian C. Mackness, Don. L. Rempel, Hao Zhang, Weidong Cui, C. Robert Matthews, Jill A. Zitzewitz, and Michael L. Gross, J. Am. Soc. Mass Spectrom., 28, 389-392 (2017).  PMC5233597

Warfarin traps human vitamin K epoxide reductase in an intermediate state during electron transfer, Guomin Shen, Weidong Cui, Hao Zhang, Fengbo Zhou, Wei Huang, Qian Liu, Yihu Yang, Shuang Li, Gregory R Bowman, J Evan Sadler, Michael L Gross, and Weikai Li, Nature Structural & Molecular Biology, 24, 69-76 (2017).  PMC5533293

Mapping the Energetic Epitope of an Antibody/Interleukin-23 Interaction with Hydrogen/Deuterium Exchange, Fast Photochemical Oxidation of Proteins Mass Spectrometry, and Alanine Shave Mutagenesis, Jing Li, Hui Wei, Stanley R. Krystek, Jr., Derek Bond, Ty M. Brender, Daniel Cohen, Jena Feiner, Nels Hamacher, Johanna Harshman, Richard Y.–C. Huang, Susan H. Julien, Zheng Lin, Kristina Moore, Luciano Mueller, Claire Noriega, Preeti Sejwal, Paul Sheppard, Brenda Stevens, Guodong Chen, Adrienne A. Tymiak, Michael L. Gross, Lumelle A. Schneeweis, Anal. Chem., 89, 2250–2258 (2017).  PMC5347259

Evolutionary fine-tuning of conformational ensembles in FimH during host-pathogen interactions, Vasilios Kalas, Jerome S. Pinkner, Thomas J. Hannan, Michael E. Hibbing, Karen W. Dodson, Alex S. Holehouse, Hao Zhang, Niraj H. Tolia, Michael L. Gross, Rohit V. Pappu, James Janetka, Scott J. Hultgren, Science Advances, 3, e1601944 (2017).  PMC5302871

Kinetic Isotope Effects and Hydrogen/Deuterium Exchange Reveal Large Conformational Changes During the Catalysis of the Clostridium acetobutylicum Spore Photoproduct Lyase, L Yang, Jagat Adhikari, Michael L. Gross, and Lei Li, Photochemistry and Photobiology, 93, 331–342 (2017).  PMC5315627

Mass spectrometry-based cross-linking study shows that the Psb28 protein binds to cytochrome b559 in Photosystem II, Daniel A. Weisz, Haijun Liu, Hao Zhang, Sundarapandian Thangapandian, Emad Tajkhorshid, Michael L. Gross, and Himadri B. Pakrasi, Proceedings of the National Academy of Sciences of the USA, 114, 2224-2229 (2017).  PMC5338524

The proteolysis adaptor, NblA, binds to the N-terminus of β-phycocyanin: Implications for the mechanism of phycobilisome degradation, Amelia Y. Nguyen, William P. Bricker, Hao Zhang, Daniel A. Weisz, Michael L. Gross, Himadri B. Pakrasi, Photosynthesis Research, 132, 95-106 (2017).  PMC5576716

Mapping the Binding Interface of VEGF and a Monoclonal Antibody Fab-1 Fragment with Fast Photochemical Oxidation of Proteins (FPOP) and Mass Spectrometry, Ying Zhang, Aaron T. Wecksler, Patricia Molina, Galahad Deperalta, Michael L. Gross, J. Am. Soc. Mass Spectrom., 28, 850-858 (2017).  PMC5624547

Protonated N-alkyl-2-nitroanilines undergo intramolecular oxidationof the alkyl chain upon collisional activation, Justin Paulose, June Cyriac, George Mathai, Daryl Giblin, Michael L. Gross, Int’l J. Mass Spectrom, 413, 75-80 (2017)

Understanding curli amyloid-protein aggregation by hydrogen–deuterium exchange and mass spectrometry, Hanliu Wang, Qin Shu, Don L. Rempel, Carl Frieden, Michael L. Gross, Int’l J. Mass Spectrom, 420, 16-23 (2017). PMC5614702

Deamidation Slows Curli Amyloid-Protein Aggregation, Hanliu Wang, Qin Shu, Carl Frieden, Michael L. Gross, Biochemistry, 56, 2865-2872 (2017).  PMC5644351

A Molecular Mechanism for Nonphotochemical Quenching in Cyanobacteria, Yue Lu, Haijun Liu, Rafael Saer, Veronica L. Li, Hao Zhang, Liuqing Shi, Carrie Goodson, Michael L. Gross, and Robert E. Blankenship, Biochemistry, 56, 2812-2823 (2017).  PMC5623595

HDX MS reveals calcium binding properties and allosteric regulation of downstream regulatory element antagonist modulator (DREAM), Jun Zhang, Jing Li, Theodore Craig, Rajiv Kumar and Michael L. Gross, Biochemistry, 56, 3523–3530 (2017).  PMC5551683

Orthogonal Mass Spectrometry-Based Footprinting for Epitope Mapping and Structural Characterization: The IL‑6 Receptor upon Binding of Protein Therapeutics, Ke Sherry Li, Guodong Chen, Jingjie Mo, Richard Y.-C. Huang, Ekaterina G. Deyanova, Brett R. Beno, Steve R. O’Neil, Adrienne A. Tymiak, and Michael L. Gross, Anal. Chem., 89, 7742–7749 (2017).  PMC5549780

Peptide-Level Interactions between Proteins and Small-Molecule Drug Candidates by Two Hydrogen−Deuterium Exchange MS-Based Methods: The Example of Apolipoprotein E3, Hanliu Wang, Don L. Rempel, Daryl Giblin, Carl Frieden, and Michael L. Gross, Anal. Chem. 89, 10687–10695 (2017).  PMC5655995

Native Mass Spectrometry, Ion mobility, and Collision-Induced Categorize Malaria Antigen/Antibody Binding, Yining Huang, Nichole D. Salinas, Edwin Chen, Niraj H. Tolia, and Michael L. Gross, J. Amer. Soc. Mass Spectrom., 28, 2515-2518 (2017).  PMC5647250

Laser-initiated Radical Trifluoromethylation of Peptides and Proteins and Its Application to Mass Spectrometry-Based Protein Footprinting, Ming Cheng, Bojie Zhang, Weidong Cui, and Michael L. Gross, Angewandte Chemie-International Edition, 56, 14007-14010 (2017).  PMC5663992

Reactive oxygen species leave a damage trail that reveals water channels in Photosystem II. D. A. Weisz, M. L. Gross, and H. B. Pakrasi, Sci. Adv., 3, eaao3013 (2017).  PMC5693562

Mass spectral studies of the biologically active stereoisomer family of e,e,e-(methanofullerene(60-63)-carboxylic acids, Michael Grayson, Joshua Hardt, Michael Gross, Subhasish K. Chakraborty, Laura Dugan, Current Anal. Chem., 14, 1-10 (2018)

Membrane Protein Structure in Live Cells: Methodology for Studying Drug Interaction by Mass Spectrometry-Based Footprinting, Guomin Shen, Shuang Li, Weidong Cui, Shixuan Liu, Yihu Yang, Michael Gross, and Weikai Li, Biochemistry, 57, 286–294 (2018).  PMC5862532

Mouse and human monoclonal antibodies protect against infection by multiple genotypes of Japanese encephalitis virus, E. Fernandez, N. Kose, M.A. Edeling, J. Adhikari, G. Sapparapu, S.M. Lazarte, C.A. Nelson, J. Govero, Michael L. Gross, Daved H. Fremont, J.E. Crowe, Jr, Michael S. Diamond MS. mBio 9, e00008-18. doi.org/10.1128/mBio.00008-18 (2018).  PMC5829823

Human IFIT3 modulates IFIT1 1 RNA binding specificity and protein stability, Britney Johnson, L.A. VanBlargan, Wei Xu, J.P. White, Chao Shan, Pei-Yong Shi, Rong Zhang, Jagat Adhikari, Michael L. Gross, Daisy W. Leung, Michael S. Diamond, and Gaya K. Amarasinghe, Immunity, 48, 487-499 (2018).

Mass Spectrometry-Based Fast Photochemical Oxidation of Proteins (FPOP) for Higher Order Structure Characterization, Ke Sherry Li, Liuqing Shi, and Michael L. Gross, Accounts of Chemical Research, 51, 736-744 (2018).  PMC5936467

Primary and higher order structure of the reaction center from the purple phototrophic bacterium Blastochloris viridis: A test for native mass spectrometry, Yue Lu, Carrie Goodson, Robert E. Blankenship, Michael L. Gross, J. Proteome Research, 17, 4, 1615-1623 (2018).  PMC5911391

Pulsed HDX Illuminates the Aggregation Kinetics of Alpha-Synuclein, the Causative Agent for Parkinson’s Disease, Eva Illes-Toth, Don Rempel, and Michael L. Gross, ACS Chem Neuroscience, 9, 1469-1476 (2018). PMC6013392

Allosteric Coupling of CARMIL and V-1 Binding to Capping Protein Revealed by Hydrogen/Deuterium Exchange, Britney Johnson, Patrick McConnell, Alex G. Kozlov, Marlene Mekel, Timothy M. Lohman, Michael L. Gross, Gaya K. Amarasinghe, and John A. Cooper, Cell-Reports, 23, 2795-2804 (2018).

Electron Cryo-microscopy Structure of Ebola Virus Nucleoprotein Reveals a Mechanism for Nucleocapsid-like Assembly. Z. Su, C. Wu, L. Shi, P. Luthra, G.D. Pintilie, B. Johnson, J.R. Porter, P. Ge, M. Chen, G. Liu, T.E. Frederick, J.M. Binning, G.R. Bowman, Z.H. Zhou, C.F. Basler, Michael L. Gross, D. W. Leung, W. Chiu, and G.K. Amarasinghe, Cell, 172, 966-978 (2018). PMC5973842

Stabilization of warfarin‐binding pocket of VKORC1 and VKORL1 by a peripheral region determines their different sensitivity to warfarin inhibition, G. Shen, S. Li, W. Cui, S. Liu, Q. Liu, Y. Yang, Michael Gross, Weikai Li, J. Thrombosis and Haemostasis, 16, 1164-1175 (2018).

Implementing Fast Photochemical Oxidation of Proteins (FPOP) as a Footprinting Approach to Solve Diverse Problems in Structural Biology, Bojie Zhang, Ming Cheng, Don Rempel, and Michael L. Gross, Methods, 144, 94-103 (2018)

MRI is a DNA Damage Response Adaptor during Classical Non-Homologous End Joining, Putzer J. Hung, Britney Johnson, Bo-Ruei Chen, Andrea K. Byrum, Andrea L. Bredemeyer, William T. Yewdell, Tanya E. Johnson, Brian J. Lee, Shruthi Deivasigamani, Issa Hindi, Parmeshwar Amatya, Michael L. Gross, Tanya T. Paull, David J. Pisapia1, Jayanta Chaudhuri, John J. H. Petrini, Nima Mosammaparast, Gaya K. Amarasinghe, Shan Zha, Jessica K. Tyler and Barry P. Sleckman, Molecular Cell, 71, 332-342 (2018)

The entropic force generated by intrinsically disordered segments can tune protein function. Nicholas D. Keul, Krishnadev Oruganty, Elizabeth T. Schaper Bergman, Nathaniel R. Beattie, Weston E. McDonald, Renuka Kadirvelraj, Michael L. Gross, Robert S. Phillips, Stephen C. Harvey, and Zachary A. Wood, Nature, 563, 584–588 (2018)

A Fast-Photochemical Oxidation of Proteins (FPOP) platform for free-radical reactions: the carbonate radical anion with peptides and proteins, Mengru Mira Zhang, Don L. Rempel, Michael L. Gross, Free Radical Biology and Medicine, 131, 126-132 (2019).

Protein-Metal-Ion Interactions Studied by Mass Spectrometry-Based Footprinting with Isotope-Encoded Benzhydrazide, Chunyang Guo, Ming Cheng, and Michael L. Gross, Analytical Chemistry, 91, 1416-1423 (2019).

Ebola Viral Protein 35 N-terminus is a Parallel Tetramer, Chamnongsak Ken Chanthamontri, David Jordan, Wenjie Wang, Chao Wu, Yanchun Lin, Tom J. Brett, Michael L. Gross, and Daisy W. Leung, Biochemistry, 58, 657–664 (2019).

Near-atomic Structure of a Giant Virus, Michael Rossmann, Qianglin Fang, Dongjie Zhu, Irina Agarkova, Jagat Adhikari, Thomas Klose, Yue Liu, Zhenguo Chen, Yingyuan Sun, Michael Gross, James Van Etten, and Xinzheng Zhang, Nature Communications, 10, Article number: 388 (2019)

Moderately-neutralizing epitopes in non-functional regions dominate the antibody response to Plasmodium falciparum EBA-140, Nichole D. Salinas, May M. Paing, Jagat Adhikari, Michael L. Gross, and Niraj Tolia, Infection and Immunity, in press

Protonation of Curcumin Triggers Sequential Double Cyclization in the Gas-Phase: An Electrospray Mass Spectrometry and DFT Study, June Cyriac, Justin Paulose, Mathai George, R. Srinivas, Daryl Giblin, and Michael L. Gross, Int J. Mass Spectrom., 438, 107-114 (2019).

Protein-Ligand Interaction by Ligand Titration, Fast Photochemical Oxidation of Proteins and Mass Spectrometry: LITPOMS. XR Liu, Mengru M. Zhang, D.L. Rempel, and Michael L. Gross, J Am. Soc. Mass Spectrom. 30, 213-217 (2019).

Recognition of Human IgG1 by FcγReceptors: Structural Insightsfrom Hydrogen−Deuterium Exchange and Fast PhotochemicalOxidation of Proteins Coupled with Mass Spectrometry, Liuqing Shi, Tun Liu, Michael L. Gross, and Yining Huang, Biochemistry, 58, 1074-1080 (2019).

Native Mass Spectrometry, Ion Mobility, and Electron-Capture Dissociation Provide Structural Information for Gas-Phase Apolipoprotein E oligomers, Hanliu Wang, Joseph Eschweiler, Weidong Cui1, Hao Zhang1, Carl Frieden, Brandon T. Ruotolo, Michael L. Gross, J. Am. Soc. Mass Spectrom., in press


2018, ACS Award in Analytical Chemistry, American Chemical Society

2017, Election as Fellow to AAAS, American Association for the Advancement of Science

2016, Plenary Lecture, American Society for Mass Spectrometry, Sanibel Conference

2013, Opening Plenary Lecture on History on first 50 y of Mass Spectrometry (1913-1963), American Society for Mass Spectrometry, Annual Conference

2013, EAS Award for Achievements in Mass Spectrometry, Eastern Analytical Symposium

2012, Wolfgang Paul Lectureship, Mass Spectrometry Societies of Germany and Poland

2011, Mass Spectrometry Society of Japan, Honorary Lifetime Membership

2008, Bruker Daltonics Lectureship, University of Konstanz, Germany

2008, Freiser Lectureship, Purdue University

2006, J.J. Thomson Medal for Service to Int'l MS, Foundation for International Mass Spectrometry

2005, Excellence in Mentoring Award, Washington University Graduate Student Senate

2005, New Jersey Distinguished Lectureship, NJ Section ACS Mass Spectrometry Discussion Group

2004, Outstanding Mentor Award, Washington University Graduate Student Senate

2002, Midwest Award for Achievements in Chemistry, American Chemical Society

2002, Excellence in Mentoring Award, Washington University Graduate Student Senate

2001, Watkins Visiting Professor, Witchita State University

2001, Outstanding Mentor Award, Washington University Graduate Student Senate

2000, Frontiers in Chemistry Lectureship, Wayne State University

2000, Plenary Lecture, Vienna Mass Spectrometry Colloquium

2000, Plenary Lecture, EnviroAnalysis 2000

1999, Field and Franklin Award, American Chemical Society

1998, Plenary Lecture, Assoc. Official Anal. Chemists' Int'l Meeting

1998, Plenary Lecture, HPLC International Symposium

1997, Plenary Lecture, Colloquium Spectroscopicum Internationale

1997, Plenary Lecture, Igler MS Tage, Innsbruck

1996, Guest Faculty, NATO School on Biol. Mass Spectrometry

1995, Pioneers in Chemistry Series, Texas A&M University

1995, Plenary Lecture, Western Biotechnology Conference, San Diego

1995, Plenary Lecture, FDA Mass Spectrom. Symposium, Washington DC

1994, Plenary Lecture, Australia/New Zealand MS Conference, Melbourne

1993, Guest Professor, NATO Adv. Study Inst. Biol. MS, Ischia, Italy

1993, Plenary Lecture, Colloquium Spectroscopium Internationale

1993, Plenary Lecture, Taiwan Int'l Chemistry Conference

1993, Plenary Lecture, Indian Society for Mass Spectrometry

1993, Lifetime Member, Indian Society for Mass Spectrometry

1993, Kraft Lectureship, Indiana University

1992, Plenary Lecture, European Tandem Mass Spectrom. Conf.

1992, Recognized as 50 Most Cited Chemists, Institute for Scientific Information, 1984-1991

1991, Plenary Lecture, Australian Symposium on Analytical Chem.

1991, Plenary Lecture, Elsevier Anal. Advances for the 90s Symposium

1990, Van't Hoff Visiting Professor, Int'l Graduate School, University of Amsterdam

1990, Guest Pfrofessor, NATO Adv. Study Inst. in Biol. Mass Spectrometry

1988, Albright & Wilson Visiting Professor, University of Warwick

1988, Plenary Lecture, American Society for Mass Spectrometry

1987, Pioneer Award, Commonwealth of Mass "In Search for the Health Consequences of Dioxin in Our Environment."

1987, Hertel Lectureship, University of Tennessee

1987, Alan Maccoll Plenary Lectureship, British Royal Society for Mass Spectrometry

1987, Plenary Lecture, British Royal Society "Spectroscopy Across Spectrum"

1986, J.C. Karcher Lectureship, University of Oklahoma

1986, Plenary Lectureship, Versailles International Workshop on Ion-Molecule Rxs.

1984, Distinguished Lecture Series, Indiana University

1984, Plenary Lecture, Swiss/French Mass Spectrometry Conference

1984, Third Cycle Lectures, Eidegenössische Technische Hochschule Lausanne

1978, Foundation Medal for Distinguished Teaching, University of Nebraska