Department of Chemistry

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Sunil Saxena

Professor and Department Chair

Contact

711 CHVRN
Chevron Science Center, 219 Parkman Avenue

Pittsburgh, PA 15260
412-624-8680

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Research Overview

Analytical, Biophysical, and Physical Chemistry

We develop pulsed electron spin resonance methods and their application to otherwise inaccessible problems in biophysics and materials sciences. The coupling of electron spin angular momentum to its environment—as revealed by the ESR spectrum—provides rich information about the electronic, structural and dynamical properties of the molecule. We create methods that measure the precise distance between two units in a protein, in order to determine their folding patterns and conformational dynamics. These ESR Spectroscopic Rulers— based on multiple quantum coherences and double resonance experiments—are unique in that they resolve distances in the 1 - 7 nm lengthscale even on bulk amorphous materials. Much of this work is based on the use of first-principles theory to develop new experimental protocols and to analyze experimental results.

Our group continues to develop applications of these spectroscopic rulers that range from capturing the essence of structural changes - such as misfolding - in proteins, to measuring the atomic-level details of ion-permeation in a ligand gated ion-channel. We invite you to visit our group website and to contact us to explore the diversity of research projects currently underway in our group.

Projects include:

  • Pulsed ESR methods to measure distance constraints in systems containing paramagnetic metals
  • Measurement of structural and dynamical determinants of the protein-DNA interactions and functional dynamics in pentameric ligand gated ion-channels.
  • Application of the spectroscopic ruler to measure and predict global structures of nanostructured materials.
  • Role of metals in aggregation of Amyloid-b peptide.

Awards

  • Crano Memorial Lecture, ACS-Akron Section, 2014
  • Arts and Sciences Tina and David Bellet Teaching Excellence Award, 2012
  • NSF CAREER Award, 2004-2009

CV

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Publications

“19F paramagnetic relaxation based NMR for quaternary structural restraints of ion channels,” V. Bondarenko, M.M Wells, Q. Chen, K.C. Singewald, S. Saxena, Y. Xu, P. Tang ACS Chem. Bio 2019 (in press)
“Designing open metal sites in metal-organic frameworks for paraffin/olefin separations,” M.H. Mohamed, Y. Yang, L. Li, S. Zhang, J.P. Ruffley, A Gamble Jarvi, S. Saxena, G. Veser, K. J. Johnson, N. Rosi, J. Am. Chem. Soc 2019, 141 13003
“An undergraduate experiment to explore Cu(II) coordination environment in multi-histidine compounds through electron spin resonance spectroscopy,” E. P. Wagner, K. C. Gronborg, S. Ghosh, S. Saxena J. Chem. Ed. 2019, 96 1752
“Understanding and controlling the metal-directed assembly of terpyridine-functionalized coiled-coil peptides,” K. A. Scheib, N. A. Tavenor, M. J. Lawless, S. Saxena, W. S. Horne Chem Comm. 2019, 55 7752
“The effect of MnO2 of different structures on activation of peroxymonosulphate for bisphenol A degradation under acidic conditions,” J. Huang, Y. Dai, K. Singewald, C.-C. Liu, S. Saxena, H. Zhang Chem Eng. J. 2019, 370, 906
“EPR spectroscopy detects various active state conformations of the transcriptional regulator CueR,” H. Sameach, S. Ghosh, L. Gevorkyan-Airapetov, S. Saxena, S. Ruthstein Angew. Chem. Intl. Ed. 2019, 58, 3053
“Efficient localization of a metal ion within a protein by Cu2+-based EPR distance measurements,” A. Gamble Jarvi, T. F. Cunningham, S. Saxena Phys. Chem. Chem. Phys. 2019, 21, 10238
“Increasing nitroxide lifetime in cells to enable in-cell protein structure and dynamics measurements by electron spin resonance spectroscopy,” K. Singewald, M. Lawless, S. Saxena J. Magn. Reson. 2019, 299, 21
“On the use of Q-band DEER to resolve relative orientations of two double-Histidine bound Cu2+-ions in a protein,” A.G. Jarvi, K. Ranguelova, S. Ghosh, R. Weber, S. Saxena J. Phys. Chem. B 2018, 122, 10669
“Copper oxidation dynamics in Cu2-xSe nanoparticles,” D.C. Kaseman, A.G. Jarvi, X.Y. Gan, S. Saxena, and J.E. Millstone Chem. Mater. 2018, 30, 7313
“Cu(II) EPR reveals two distinct binding sites and oligomerization of innate immune protein Calgranulin C,” S. Ghosh, V. Garcia, K. Singewald, S. Damo, and S. Saxena Appl. Magn. Reson. 2018, 49, 1299
“Rotamer modelling of Cu(II) spin labels based on the double-Histidine motif,” S. Ghosh, S. Saxena, G. Jeshke Appl. Magn. Reson. 2018, 49, 1281
“Programmable topology in new families of heterobimetallic metal-organic frameworks,” P.F. Muldoon, C. Liu, C.C. Miller, S.B. Koby, A.G. Jarvi, T.-Y. Luo, S. Saxena, M. O’Keeffe, N.L. Rosi, J. Am. Chem. Soc. 2018, 140, 6194
“ESR shows that the C-terminus of Ligand Free Human Glutathione S-Transferase A1-1 exists in two conformations,” M. J. Lawless, J. R. Pettersson, G. S. Rule, F. Lanni, S. Saxena Biophys J. 2018, 114, 592
“The Cu(II)-nitrilotriacetic acid complex improves loading of a-helical double-histidine sites for precise distance measurements by pulsed ESR,” S. Ghosh, M. J. Lawless, G. S. Rule, S. Saxena J. Magn. Reson. 2018, 286, 163
“On the use of Cu(II)-iminodiacetic acid complex in double-Histidine based distance measurements by pulsed electron spin resonance,” M. J. Lawless, S. Ghosh, T. F. Cunningham, A. Shimshi, and S. Saxena Phys. Chem. Chem. Phys. 2017, 19, 20959
“An analysis of nitroxide based distance measurements by pulsed ESR spectroscopy in cell-extract and in-cell,” M. J. Lawless, A. Shimshi, T. F. Cunningham, M. Kinde, P. Tang, and S. Saxena ChemPhysChem. 2017, 18, 1653
“Nucleotide-independent Cu(II)-based distance measurements in DNA by pulsed ESR,” M. J. Lawless, J. L. Sarver, S. Saxena Angew Chem 2017, 56, 2115