Carnegie Mellon University Department of Chemistry
photo of Yisong (Alex) Guo

Yisong (Alex) Guo

Assistant Professor

Carnegie Mellon University

email:

(412) 268-5059

Fax: (412) 268-1704

office: MI 552

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Faculty & Research

Yisong (Alex) Guo

Assistant Professor

Research Areas

Spectroscopy, Bioinorganic Chemistry, Mössbauer and EPR Spectroscopy, Synchrotron Radiation Techniques, Nuclear Resonance Vibrational Spectroscopy (NRVS), Synchrotron Mössbauer, Metalloproteins, Enzyme Mechanisms, Transition Metal Complexes, Electronic Structures, Density Functional Theory.

Research Description

Metalloproteins play essential roles in many key biological processes, including photosynthesis, respiration, nitrogen fixation and carbon cycle, antibiotics biosynthesis, gene regulation, post transcriptional modification, bio-signal sensing, and DNA/RNA repair. In these biological processes, an astounding array of chemical transformations with high stereo- and regio-selectivities is achieved by metal centers buried inside the protein scaffold of metalloproteins. Studies of these metal centers in both geometric and electronic level not only can help us reveal the fundamental chemical principles underpinning these biological processes, also provide valuable guidelines for designing and synthesizing efficient and inexpensive catalysts to perform some of these important yet challenging chemical transformations, such as water oxidation, dinitrogen reduction, selective C-H functionalization.

Our main research focus is iron containing metalloproteins, in particular, small molecule (N2, H2, O2 etc.) activating enzymes, such as nitrogenases, hydrogenases, and oxygenases. Various advanced spectroscopic methods are utilized to gain information regarding iron center changes, both geometric and electronic, during enzyme catalytic cycles. Spectroscopic studies are coupled with Density Functional Theory (DFT) calculations to establish structural models and further identify reaction mechanisms. The ultimate goal of our research is to impact favorably on alternative energy research and human health.

The spectroscopic methods we use include Mössbauer Spectroscopy, Electron Paramagnetic Resonance (EPR) Spectroscopy, Nuclear Resonance Vibrational Spectroscopy (NRVS), and Synchrotron Mössbauer.

Mössbauer spectroscopy arguably has the highest information content of any spectroscopic methods on studies of iron containing systems. It detects all iron in a given sample, and determines their oxidation, spin states, and precise quantification of iron in different local environments. It is a high-resolution technique, which allows one to probe the electronic structure of iron sites in great detail through the hyperfine coupling between electronic states and nuclear states. EPR spectroscopy is a high sensitivity technique; it detects paramagnetic systems and reveals their electronic structures through electronic Zeeman Effect.

Recent developments of synchrotron radiation (SR) facilities enable us to utilize SR sources for Mössbauer spectroscopy in replacement of traditional radioactive sources. The advantage of Synchrotron Mössbauer over the conventional lab-based Mössbauer is that it can have higher spectral resolution, shorter measurement time, and the capability of measuring smaller samples, which are crucial for studies on metalloproteins. The advancement of modern synchrotron radiation sources also promotes the development of a new type of vibrational spectroscopic technique, Nuclear Resonance Vibrational Spectroscopy (NRVS). NRVS detects nuclear excitation coupled molecular vibration excitation (or de-excitation), which conceptually resembles Raman scattering. Yet, compared with Raman and Infrared techniques, NRVS has much higher element selectivity and less restrictive selection rules. It allows us study structures and dynamics of iron centers in metalloproteins by selectively probing iron related vibrations in the far IR region (essentially down to 0 cm-1) without the interference of protein scaffold and solvent vibrations.

With continuous development of synchrotron radiation facilities, new synchrotron radiation with many orders of magnitude higher in intensity and extremely smaller beam size (sub-micron to nanometers) than those in use today will be available in the near future. In collaboration with groups at synchrotron radiation facilities, we will develop imaging techniques using Mössbauer spectroscopy to study iron cofactors in organelles and whole cells.

Education and Appointments
2013–present Assistant Professor, Department of Chemistry, Carnegie Mellon University
2012–2013 Postdoctoral Research Associate, Department of Chemistry, the Pennsylvania State University.
Advisors: Prof. J. Martin Bollinger and Prof. Carsten Krebs
2009–2012 Postdoctoral Research Associate, Department of Chemistry, Carnegie Mellon University.
Advisors: Prof. Eckard Münck and Prof. Emile L. Bominaar (theory)
2003–2009 Ph.D. Department of Applied Science, University of California, Davis
1998–2002 B.S., Department of Material Science, Fudan University, China
Selected Publications

Wei-chen Chang, Yisong Guo, Chen Wang, Susan E. Butch, Amy C. Rosenzweig, Amie K. Boal, Carsten Krebs, J. Martin Bollinger Jr. “Mechanism of the C5 Stereoinversion Reaction in the Biosynthesis of Carbapenem Antibiotics” Science, 2014, 343, 1040-1044.

Chen Wang, Wei-chen Chang, Yisong Guo, Hui Huang, Spencer C. Peck, Maria E. Pandelia, Geng-min Lin, Hung-wen Liu, Carsten Krebs, J. Martin Bollinger Jr. "Evidence that the Fosfomycin-Producing Epoxidase, HppE, Is a Non-Heme-Iron Peroxidase" Science, 2013, 342, 991-995.

Yisong Guo, Yoshitaka Yoda, Xiaowei Zhang, Yuming Xiao, Stephen P. Cramer “Synchrotron Radiation Based Nuclear Resonant Scattering: Applications to Bioinorganic Chemistry” Book Chapter in Mössbauer Spectroscopy: Applications in Chemistry, Biology, Nanotechnology, Industry, and Environment, Wiley, 2013 in press.

Yisong Guo,Eric Brecht, Kristen Aznavour, Jay C. Nix, Yuming Xiao, Hongxin Wang, Simon J. George, Robert Bau, Stephen Keable, John W. Peters, Michael W. W. Adams, Francis E. Jenney Jr. Wolfgang Sturhahn, E. Ercan Alp, Jiyong Zhao, Yoshitaka Yoda, Stephen P. Cramer “Nuclear Resonance Vibrational Spectroscopy (NRVS) of Rubredoxin and MoFe Protein Crystals” Hyperfine Interactions 2013, 222, S77-S90.

Aidan R. McDonald, Yisong Guo, Van V. Vu, Victor G. Young, Emile L. Bominaar, Eckard Münck, Lawrence Que, Jr. “A Mononuclear Carboxylate-Rich Oxoiron(IV) Complex”. Chemical Science, 2012, 3, 1680-1693.

Devrani Mitra, Simon J. Geroge, Yisong Guo, Saeed Kamali, Stephen Keable, John W. Peters, Vladimir Pelmenschikov, David A Case, Stephen P. Cramer “Characterization of [4Fe-4S] Cluster Dynamics and Structure in Nitrogenase Fe Protein at Three Oxidation Levels via Combined NRVS, EXAFS and DFT Analyses” Journal of the American Chemical Society 2012, 135, 2530-2543.

Jason England, Yisong Guo, Katherine M. Van Heuvelen, Matthew A. Cranswick, Gergory T. Rohde, Emile L. Bominaar, Eckard Münck, Lawrance Que, Jr. “A Trigonal Bipyramidal High-Spin Oxoiron(IV) Complex Having a cis-Labile Site” Journal of the American Chemical Society,2011, 133, 11880-11883.

Jason England, Yisong Guo, Erik R. Farquhar, Victor G. Young Jr. Eckard Münck, and Lawrence Que Jr. “The Crystal Structure of a High-Spin Oxoiron(IV) Complex and Characterization of Its Self-Decay Pathway” Journal of the American Chemical Society 2010, 132, 8635-8644.

Jessica Garber-Morales, Gregory P. Holmes-Hampton, Ren Miao, Yisong Guo, Eckard Münck, and Paul A. Lindahl “Biophysical Characterization of Iron in Mitochondria Isolated from Respiring and Fermenting Yeast” Biochemistry 2010, 49, 5436-5444.

Yisong Guo, Hongxin Wang, Yuming Xiao, Sonja Vogt, Rudolf K. Thauer, Seigo Shima, Phillip I. Volkers, Thomas B. Rauchfuss, Vladimir Pelmentschikov, David A. Case, Ercan E. Alp, Wolfgang Sturhahn, Yoshitaka Yoda, and Stephen P. Cramer “Characterization of the Fe Site in Methanothermobacter marburgensis Hydrogenase (mHmd) via Nuclear Resonance Vibrational Spectroscopy (NRVS)” Inorganic Chemistry 2008, 47, 3969-3977.