Saxena Group is focused on developing Fourier Transform electron spin resonance and its application to otherwise inaccessible problems in biophysics. 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. Saxena group creates the 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 1-16 nm length scale 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.
His 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. The main projects of his group 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-β peptide.
- "Nonlinear-least-squares analysis of slow-motion EPR spectra in one and two dimensions using a modified Levenberg–Marquardt algorithm," D. E. Budil, S. Lee, S. Saxena, J. H. Freed, Journal of Magnetic Resonance, Series A 120, 155 (1996)
- "Amplification of xenon NMR and MRI by remote detection," A. J. Moulé, M. M. Spence, S. I. Han, J. A. Seeley, K. L. Pierce, S Saxena, A. Pines. Proceedings of the National Academy of Sciences 100, 9122 (2003)
- "Double quantum two-dimensional Fourier transform electron spin resonance: distance measurements," S. Saxena, J. H. Freed, Chemical physics letters 251,102 (1996)
- "Theory of double quantum two-dimensional electron spin resonance with application to distance measurements," J Freed, S. Saxena, Jounal of Chemiical Physics 107, 1317-1340 (1997).
- "Direct evidence that all three histidine residues coordinate to Cu (II) in amyloid-β1− 16," B. Shin, S. Saxena, Biochemistry 47, 9117 (2008)
- “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, Biophysical Journal 114, 592 (2018)
- “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., 286, 163 (2018)
- “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., 19, 20959 (2017)
- “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., 18, 1653 (2017)
- “Nucleotide-independent Cu(II)-based distance measurements in DNA by pulsed ESR,” M. J. Lawless, J. L. Sarver, S. Saxena, Angew Chem, 56, 2115 (2017)