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Electron Paramagnetic Resonance (EPR) Facility

Recent publications and presentations from this Facility:














Dr. Andrei Astashkin                                                   Dr. Arnold Raitsimring

Supervisor                                                   Former Supervisor

  1. A.V. Astashkin, E.L. Klein, J.H. Enemark. Toward modeling the high chloride, low pH form of sulfite oxidase: Ka-band ESEEM of equatorial chloro ligands in oxomolybdenum(V) complexes. J. Inorg. Biochem. 101 (2007) 1623-1629.
  2. A.V. Astashkin, K. Johnson-Winters, E.L. Klein, R.S.Byrne, A.M. Raitsimring, J.H. Enemark. Direct Demonstration of the Presence of Coordinated Sulfate in the Reaction Pathway of Arabidopsis thaliana Sulfite Oxidase Using 33S Labeling and ESEEM Spectroscopy. J. Am. Chem. Soc 129 (2007) 14800-14810.
  3. A.M. Raitsimring, A.V. Astashkin, D. Baute, D. Goldfarb, O.G. Poluektov, M.P. Lowe, S.G. Zech and P. Caravan. Pulsed 17O ENDOR Spectroscopy. ChemPhysChem 7 (2006) 1590-1597.
  4. J.H. Enemark, A.V. Astashkin and A.M. Raitsimring. Investigation of the coordination structures of the molybdenum(V) sites of sulfite oxidizing enzymes by pulsed EPR spectroscopy. Dalton Trans. (2006) 3501-3514.
  5. A.V. Astashkin, J.H. Enemark and A.M. Raitsimring. 26.5-40 GHz Ka-band pulsed EPR spectrometer. Concepts in Magnetic Resonance. Part B. Magnetic Resonance Engineering. 29B (2006) 125-136.
  6. A.M. Khenkin, P. Carl, D. Baute, A.M. Raitsimring, A.V. Astashkin, L.J.W. Shimon, D. Goldfarb and R. Neumann. Structural and EPR/ENDOR/ESEEM Spectroscopic Investigations of a Vanadomolybdate Keggin-Type Polyoxometalate in Organic Solvent. Inorg. Chim. Acta 359 (2006) 3072-3078.
  7. A.V. Astashkin, J. Seravalli, S.O. Mansoorabadi, G.H. Reed and S.W. Ragsdale. Pulsed Electron Paramagnetic Resonance Experiments Identify the Paramagnetic Intermediates in the Pyruvate Ferredoxin Oxidoreductase Catalytic Cycle. J. Am. Chem. Soc. 128 (2006) 3888-3889.
  8. S.G.Zech, W.C.Sun, V.Jacques, P.Caravan, A.V.Astashkin, A.M.Raitsimring. Probing the Water Coordination of Protein-Targeted MRI Contrast Agents by Pulsed ENDOR Spectroscopy. ChemPhysChem 6 (2005) 2570-2577.
  9. C.Feng, H.L.Wilson, G.Tollin, A.V.Astashkin, J.T.Hazzard, K.V.Rajagopalan, J.H.Enemark. The Pathogenic Human Sulfite Oxidase Mutants G473D and A208D Are Defective in Intramolecular Electron Transfer. Biochemistry 44 (2005) 13734-13743.
  10. A.V.Astashkin, F.Neese, A.M.Raitsimring, J.J.A.Cooney, E.Bultman, J.H.Enemark.Pulsed EPR Investigations of Systems Modeling Molybdenum Enzymes: Hyperfine and Quadrupole Parameters of Oxo-17O in [Mo17O(SPh)4]- J. Am. Chem. Soc. 127 (2005) 16713-16722.
  11. A.V.Astashkin, B.L.Hood, C.Feng, R.Hille, R.R.Mendel, A.M.Raitsimring, J.H.Enemark. Structures of the Mo(V) Forms of Sulfite Oxidase from Arabidopsis thaliana by Pulsed EPR Spectroscopy. Biochemistry 44 (2005) 13274-13281.
  12. A.M.Raitsimring, A.V.Astashkin, O.G.Poluektov and P.Caravan. "High field pulsed EPR and ENDOR of Gd3+ complexes in glassy solutions." Appl. Magn. Reson. 28 (2005) 281-295.
  13. A.V.Astashkin, A.M.Raitsimring, F.A.Walker, C.Rensing and M.McEvoy. "Characterization of the Copper(II) Binding Site in the Pink Copper Binding Protein CusF by Electron Paramagnetic Resonance Spectroscopy." J. Biol. Inorg. Chem.10 (2005) 221-230.
  14. M.M.Cosper, F.Neese, A.V.Astashkin, M.D.Carducci, A.M.Raitsimring and J.H.Enemark. "Determination of the g-Tensors and Their Orientations for cis,trans-(L-N2S2)MoVOX (X = Cl, SCH2Ph) by Single-Crystal EPR Spectroscopy and Molecular Orbital Calculations." Inorg. Chem. 44 (2005) 1290-1301.
  15. A.V.Astashkin, C.J.Feng, A.M.Raitsimring and J.H.Enemark. "17O ESEEM Evidence for Exchange of the Axial Oxo Ligand in the Molybdenum Center of the High pH Form of Sulfite Oxidase." J. Am. Chem. Soc. 127 (2005) pp. 502-503.
  16. Raitsimring, A. M.; Astashkin, A. V.; Baute, D.; Goldfarb, D.; Caravan, P.; "W-Band 17O Pulsed Electron Nuclear Double Resonance Study of Gadolinium Complexes with Water." J. Phys. Chem. A.; 2004; 108; 7318-7323.
  17. Utschig, L. M.; Astashkin, A. V.; Raitsimring, A. M.; Thurnauer, M. C.; Poluektov, O. G. "Pulsed EPR/ENDOR Characterization of the Cu2+ Surface Site in Photosynthetic Bacterial Reaction Centers." J. Phys. Chem. B. ; 2004; 108; 11150-11156.
  18. Astashkin, A. V.; Raitsimring, A. M.; Caravan, P. "Pulsed ENDOR Study of Water Coordination to Gd3+ Complexes in Orientationally Disordered Systems." J. Phys. Chem. A.; 2004; 108(11); 1990-2001
  19. A. M. Tyryshkin, S. A. Lyon, A. V. Astashkin and A. M. Raitsimring. "Electron spin relaxation times of phosphorus donors in silicon." Physical Review B 68, 193207, 2003.
  20. John H. Enemark, A. Raitsimring, Andrei V. Astashkin, "Various-frequency pulsed EPR studies of Molybdenum Enzymes: Structure of Molybdenum Enzymes" in ACS Symposium Series, vol 858 (2003), J.Telser, Ed., pp. 179-192
  21. P.Caravan, A. V. Astashkin, and A. M. Raitsimring. The Gadolinium(III)-Water Hydrogen Distance in MRI Contrast Agents. Inorg.Chem. 42, 3972 - 3974; (2003).
  22. Polt, R.; Kelly, B. D.; Dangel, B. D.; Tadikonda, U. B.; Ross, R. E.; Raitsimring, A.; Astashkin, A. V." Optically Active 4- and 5-Coordinate Transition Metal Complexes of Bifurcated Dipeptide Schiff Bases" Inorg. Chem.; 2003; 42, 566-574.
  23. A. Raitsimring, A.V. Astashkin, Ch. Feng, J.H. Enemark, Kimberly Johnson Nelson, K. V. Rajagopalan "Pulsed EPR studies of the exchange able proton at the molybdenum center of dimethyl sulfoxide reductase" J. Biol Inorg Chem .2003, 8: 95-104.
  24. A. V. Astashkin and A. M. Raitsimring "Electron spin echo envelope modulation theory for high electron spin systems in weak crystal field" J. Chem. Phys.,117,6121-6132, 2002
  25. A. V. Astashkin, A. M.Raitsimring C. Feng, J.L.Johnson K.V. Rajagopalan, and J. H. Enemark "The Mo-OH Proton of the Low- pH Form of Sulfite Oxidase: Comparison of the Hyperfine Interactions Obtained from Pulsed ENDOR, CW-EPR and ESEEM Measurements" Appl.Magn.Reson. 22, 421-430, 2002.
  26. M. Rivera, GA.Cagnian, A.V. Astashkin, A.Raitsimring, T. Kh. Shokhireva, and F. A. Walker Models of the low spin iron(III) hydroperoxide intermidiate of heme oxygenase: Magnetic Resonance Evidence for thermodinamic Stabili- sation of the dxy electronic state at ambient temperature. J. Am. Chem. Soc, 124, 6077-6089, 2002.
  27. A.V. Astashkin, A. Raitsimring, Ch. Feng, J.L. Johnson, K. V. Rajagopalan, and John H. Enemark, "Pulsed ENDOR studies of non-exchangeable protons near the Mo(V) center of sulfite oxidase. 1. Direct detection of the a-proton of the co- ordinated cysteinyl residue and structural implications for the active site" J. Am. Chem. Soc, 124(21); 6109-6118. 2002.
  28. R Codd, A V. Astashkin, A. Pacheco, Arnold M. Raitsimring and John H. Enemark "Pulsed ELDOR spectroscopy of the Mo(V)/Fe(III) state of sulfite oxidase prepared by one- electron reduction with Ti(III) citrate", J.Biol.Inorg. Chem., 7, 338-350, 2002.
  29. A.Astashkin, A.Raitsimring, A. Kennedy, T.Kh, Shokhireva and F.A.Walker "Pulsed EPR Charac terization of the low spin Iron(III) Porphyrinate Complexes with Phenyl Isocyanide Ligands Having the dxy Orbital ground state" J.Phys.Chem A, 106, 1 74-82, 2002.


Conference Presentations:

  1. A.Raitsimring, A.V.Astashkin, P. Caravan. The ESEEM and pulsed ENDOR of high spin /weak crystal field ions. 26 International EPR Symposium, Denver, CO, July 27 - 31, 2003. (poster+oral )
  2. A M. Raitsimring, A V. Astashkin, C. Feng, J.H. Enemark, K E. Johnson, and K. V. Rajagopalan. "Pulsed EPR studies of the exchangeable proton at the Molybdenum center of DMSO reductase." In Abstracts : 25rd International EPR Symposium, Denver, CO, July 28 - August 1, 2002.
  3. A. M. Tyryshkin, S. A. Lyon, A. V. Astashkin, and A. Raitsimring "MECHANISMS OF ELECTRON SPIN RELAXATION OF PHOSPHORUS DONORS IN SILICON". 25rd International EPR Symposium, Denver, CO, July 28 - August 1, 2002.
  4. A. Raitsimring, A. V. Astashkin, J. H. Enemark, L. Johnson, and K. V. Rajagopalan. "Comparative Pulsed EPR Study of the Mo(V) Centers of Chicken and Human Sulfite Oxidase". In Abstracts: 24rd International EPR Symposium, Denver, CO, July 29 - August 2, 2001.
  5. A. V. Astashkin, A. M. Raitsimring, A. Kennedy, T. Kh. Shokhireva and F. A.Walker. "Pulsed EPR Characterization of the low spin Iron(III) Porphyrinate Complexes with Phenyl Isocyanide Ligands Having the dxy Orbital ground state". In Abstracts: 24rd International EPR Symposium, Denver, CO, July 29 - August 2, 2001.
  6. A. V. Astashkin, R. Codd, J. H. Enemark, M. L. Mader, A. Pacheco, A. M. Raitsimring, "Variable Frequency ESEEM Spectroscopy of Metal Sites: Direct Detection of Nearby Protons and Coordinated Oxygen Atoms," 34th International Conference on Coordination Shemistry, Edinburgh, Scotland, July 9-14, 2000 (oral presentation).
  7. A. V. Astashkin, A. M. Raitsimring and F. A. Walker, "Electronic Structure of the Fe(III)-Tetraphenylchlorin- bis-Imidazole Complex as Determined by ESEEM and Pulsed ENDOR Techniques," In Abstracts of 23rd International EPR Symposium, July 30 –August 3, 2000, Broomfield, CO (poster presentation).
  8. A. V. Astashkin, A. M. Raitsimring, R. Codd, M. L. Mader, A. Pacheco and J. H.Enemark, "Advanced ESEEM Studies of the High- and Low-pH Forms of Chicken Liver Sulfite Oxidase." In Abstracts of 23rd International EPR Symposium July 30 - August 3, 2000, Broomfield, CO (poster presentation).