Faculty Directory

F. Ann Walker

Regents Professor Emerita - Retired
Degrees and Appointments: 
B.A. 1962, The College of Wooster
Ph.D. 1966, Brown University
Postdoc 1966-67, UCLA
Assistant Professor of Ch 1967-70, Ithaca College
Regents Professor of Chem 2001-2013, The University of Arizona
Awards and Honors: 
Elected Fellow, American Chemical Society, 2011
Chair, Division of Inorganic Chemistry, American Chemical Society, 2010
Galileo Circle Fellow, College of Science, University of Arizona, 2009
Alfred Bader Award in Bioinorganic Chemistry, American Chemical Society, 2006
Alexander von Humboldt Senior Research Award, 2003-2004
Francis P. Garvin - John M. Olin Medal of the American Chemical Society, 2000
Research Summary: 

We study a wide range of bioinorganic and biological systems, all of which fall under the general theme of gaining a better understanding of the heme centers in heme proteins that are vital to the life of almost all living organisms. The overall goals of this research are to characterize the nitrosylheme proteins from blood-sucking insects. Nitric oxide has been shown to be an important neurotransmitter, vasodilator, and other chemical messenger. We have recently shown that Rhodnius prolixus (the "kissing bug")1 and Cimex lectularius (the bedbug)2 each have at least one NO-carrying heme protein in their saliva that helps them succeed in their goal of living on the blood of higher animals. We are investigating the 3-D structures, spectroscopy (NMR, EPR, UV-vis, MCD, Mössbauer, Nuclear Inelastic Scattering and resonance Raman), thermodynamics (kinetics and equilibria of NO binding, and reduction potentials in the absence and presence of NO) of the NO-binding heme proteins from both of these insects3. Current research on these proteins includes preparation and investigation of the 15N-labeled proteins in order to study their pico- to nanosecond and micro- to millisecond timescales by NMR spectroscopic methods. We have completed and published our study of NP2-NO,4 and have submitted our study of NP4 as compared to NP25 for publication.


  1. J. M. C. Ribeiro, J. M. H. Hazzard, R. Nussenzveig, D. Champagne, F. A. Walker (1993) "Reversible Binding of Nitric Oxide by a Salivary Nitrosylheme Protein from the Blood Sucking Insect, Rhodnius prolixus," Science 260, 539.
  2. J. G. Valenzuela, F. A. Walker, J. M. C. Riberiro (1995) "A Salivary Nitrophorin (NO-carrying Heme Protein) in the Bedbug. Cimex lectularius," J. Exper. Biol. 198, 1519.
  3. F. A. Walker (2005) "Nitric Oxide Interaction with Insect Nitrophorins, and Thoughts on the Electron Configuration of the {FeNO}6 Complex," J. Inorg Biochem. 99, 216-236.
  4. Muthu, D.; Berry, R. E.; Zhang, H.; Walker, F. A. (2013) "NMR Studies of the Dynamics of Nitrophorin 2 Bound to Nitric Oxide," Biochemistry 52, 7910-7925.
  5. Berry, R. E.; Muthu, D.; Yang, F.; Zhang, H.; Walker, F. A. (2014) "NMR Studies of the Dynamics of High-Spin Nitrophorins: Comparative Studies of NP4 and NP2 at Close to Physiological pH," Submitted to Biochemistry.
Publications: 

Berry, R. E.; Shokhireva, T. Kh.; Filippov, I.; Shokhirev, M. N.; Zhang, H.; Walker, F. A. (2007) "Effect of the N-Terminus on Heme Cavity Structure, Ligand Equilibrium and Rate Constants, and Reduction Potentials of Nitrophorin 2 from Rhodnius prolixus," Biochemistry 46, 6830-6843. (DOI: 10.1021/bi7002263)

Berry, R. E.; Shokhirev, M. N.; Ho, A. Y. W.; Yang, F.; Shokhireva, T. K.; Zhang, H.; Weichsel, A.; Montfort, W. R.; Walker, F. A. (2009) Effect of Mutation of Carboxylate Side-Chain Amino Acids Near the Heme on the Midpoint Potentials and Ligand Binding Constants of Nitrophorin 2 and its NO, Histamine and Imidazole Complexes," J. Am. Chem. Soc. 131, 2313-2327. (DOI: 10.1021/ja00006a066)

Yang, F.; Knipp, M.; Berry, R. E.; Shokhireva, T. K.; Zhang, H.; Walker, F. A. (2009) "1H and 13C NMR Spectroscopic Studies of the Ferriheme Resonances of the Low- Spin Imidazole, Histamine and Cyanide Complexes of wt Nitrophorin 2 and NP2(V24E) as a Function of pH," J. Biol. Inorg. Chem. 14, 1077-1095. (DOI: 10.1007/200775-009-00551-3)

Singh, R.; Berry, R. E.; Yang, F.; Zhang, H.; Walker, F. A.; Ivancich, A. I. (2010) "The Unprecedented Peroxidase-like Activity of Rhodnius prolixus Nitrophorin 2: Identification of the [FeIV=O Por.]+ and [FeIV=O Por](Tyr38.) Intermediates and Their Role(s) in Substrate Oxidation," Biochemistry 49, 8857-8872.

Shokhireva, T. K.; Berry, R. E.; Zhang, H.; Walker, F. A. (2011) "NMR Studies of Nitrophorin Distal Pocket Side Chain Effects on the Heme Orientation and Seating of NP2 as Compared to NP1," J. Inorg. Biochem. 105, 1238-1257. (DOI: 10.1016/j.jinorgbio.2011.06.001) PMCID: PMC3155619

Moeser, B.; Janoschka, A.; Wolny, J. A.; Paulsen, H.; Filippov, I.; Berry, R. E.; Zhang, H.; Chumakov, A. I.; Walker, F. A.; Schünemann, V. (2012) "Nuclear Inelastic Scattering and Mössbauer Spectroscopy as Local Probes for Ligand Binding Modes and Electronic Properties in Proteins: Vibrational Behavior of a Ferriheme Center Inside a Β-Barrel Protein," J. Am. Chem. Soc. 134, 4216-4228. (DOI: 10.1021/ja210067t) PMCID: PMC3296872

Berry, R. E.; Muthu, D.; Garrett, S. A.; Shokhireva, T. K.; Zhang, H.; Walker, F. A. (2012) "Native N-Terminus Nitrophorin 2 from the Kissing Bug: Similarities to and Differences from NP2(D1A)," Chem. Biodiv. 9, 1739-1755. (DOI: 10.1002/cbdv.201100449) PMCID:PMC3523740

Shokhireva, T. K.; Walker, F. A. (2012) "Assignment of the 1H NMR Resonances of Protein Residues in Close Proximity to the Heme of the Nitrophorins: Similarities and Differences among the Four Proteins from the Saliva of the Adult Blood-Sucking Insect, Rhodinus prolixus," J. Biol. Inorg. Chem. 17, 911-926; 1303. (DOI: 10.1007/s00775-012-0908-x) PMID: 27711328

Abriata, L. A.; Zaballa M-E.; Berry, R. E.; Yang, F.; Zhang, H.; Walker, F. A.; Vila, A. J. (2013) "Electron Spin Density on the Axial His Ligand of High-Spin and Low-Spin Nitrophorin 2 Probed by Heteronuclear NMR Spectroscopy," Inorg. Chem. 52, 1285-1295. (DOI: 10.1021/ic301805y)

Astashkin,* A. V.; Walker, F. A. (2013) "Determination of the Principal g-Values of Type I or Highly-Anisotropic Low Spin (HALS) Ferriheme Centers in Frozen Solutions," J. Magn. Reson. 231, 15-21.PMID 23562666

Weber, B.;* Walker, F. A.; Karaghiosoff, K. (2013) "Proton NMR Investigations of Intermediate Spin Iron(III) Complexes with Macrocyclic N42- Ligands," Z. Anorg. Allg. Chem. 639, 1498-1503

Muthu, D.; Berry, R. E.; Zhang, H.; Walker, F. A. (2013) "NMR Studies of the Dynamics of Nitrophorin 2 Bound to Nitric Oxide," Biochemistry 52, 7910-7925. (DOI: 10.1021/bi010396) PMID: 24116947.

Auerbach, H.; Faus, I.; Wolny, J. A.; Walker, F. A.; Chumakov, H.; Ogata, H.; Knipp, M.; Schünemann, V. (2014) "Nitric Oxide Heme Interactions in Nitrophorin 7 Investigated by Nuclear Inelastic Scattering," Hyperfine Interactions 226, 439-443. (DOI 10.1007/s10751-013-0982-7)

Berry, R. E.; Muthu, D.; Shokhireva, T. K.; Garrett, S. A.; Goren, A. M.; Zhang, H.; Walker, F. A. (2014) "NMR Investigations of Nitrophorin 2 Belt Side Chain Effects on Heme Orientation and Seating of Native N-Terminus NP2 and NP2(D1A)," J. Biol. Inorg. Chem. 19, 577-593. (DOI: 10.1007/s00775-013-1063-8) PMID: 24292244.

Berry, R. E.; Yang, F.; Shokhireva, T. K.; Amoia, A.; Garrett, S. A.; Goren, A. M.; Korte, S. R.; Zhang, H.; Weichsel, A.; Montfort, W. R.; Walker, F. A. (2014) "Dimerization of Nitrophorin 4 at Low pH: Comparison to the K1A Mutant of Nitrophorin 1," Submitted to Biochemistry.

Berry, R. E.; Muthu, D.; Yang, F.; Zhang, H.; Walker, F. A. (2014) "NMR Studies of the Dynamics of High-Spin Nitrophorins: Comparative Studies of NP4 and NP2 at Close to Physiological pH," Submitted to Biochemistry