Julie A. Kovacs

Julie A. Kovacs, PhD.Professor of Chemistry
Ph.D. Harvard University, 1986

(Bioinorganic and Inorganic Chemistry )

(206) 543-0713

Email: kovacs@chem.washington.edu
Kovacs group website

Research Interests

Transition-metal-containing enzymes (metalloenzymes) promote a number of critical biological processes ranging from the biosynthesis of neurotransmitters, and hormones, to DNA replication and repair, the conversion of electrochemical to chemical energy, and the photosynthetic production of dioxygen (O2). The molecular-level details of metalloenzyme functionImage1 emerge from several complementary lines of study, at the interface of chemistry, biology, and physics. By modeling the metal ion’s local environment and making systematic changes to this environment, one can determine, at the molecular-level, how reactivity correlates with structural, magnetic, and spectroscopic properties.


The highly covalent nature of metal-thiolate bonds impart unique properties that serve to promote catalytic reactions. Thiolates favor coordinatively unsaturated geometries, stabilize higher oxidation states, facilitate electron and H-atom transfer reactions, as well as product release, and lower the activation barrier to O2 binding. Thiolate-ligated transition-metal complexes tend to be intensely colored, and low-spin, making it easy to spectroscopically monitor reactivity. 


The general approach used by the Kovacs lab involves the design of nitrogen- and sulfur-containing organic molecules with a molecular architecture that enforces a desired stereochemistry around the metal ion. We then examine the reactivity of the resulting synthetic transition-metal complexes, and look for correlations between structure and properties, such as spin-state and electronic structure, by systematically altering the organic framework of our ligands. Reactivity of these models is then compared on the basis of kinetic and thermodynamic parameters. Techniques used by our group include low temperature electronic absorption spectroscopy, EPR, electrochemistry, and X-ray crystallography. 


The Kovacs group reported the first and only examples of biomimetic superoxide reductase analogues, the only examples of metastable thiolate-ligated Fe(III)-OOH intermediates, and the first and only crystallographically characterized Mn(III)-OOR. Manganese peroxos are implicated as key intermediates in DNA repair, photosynthetic O2-evolution, and the metabolism of prostaglandins. Iron-peroxos are implicated as key intermediates in the biosynthesis of neurotransmitters, fatty acids, and steroids.

Representative Publications

 

Coggins, M. K.; Brines, L. M.; Kovacs, J. A. “Synthesis and Structural Characterization of a Series of Mn(III)-OR Complexes, Including a Water-Soluble Mn(III)-OH that Promotes Aerobic Hydrogen Atom Transfer.” Inorg. Chem. 2013, 52, 0000 (ASAP).

http://dx.doi.org/10.1021/ic401234t

 

Coggins, M. K.; Toledo, S.; Kovacs, J. A. “Isolation and Characterization of an Unsupported, Hydroxo-Bridged Iron(III,III)(μ-OH)2 Diamond Core Derived from Dioxygen,”  Inorg. Chem. 2013 , 52, 0000 (in press).

 

Coggins, M. K.; Sun, X.; Kwak, Y.; Solomon, E. I.; Rybak-Akimova, E.; Kovacs, J. A. “Characterization of Metastable Intermediates Formed in the Reaction Between a Mn(II) Complex and Dioxygen, Including a Crystallographic Structure of a Binuclear Mn(III)-Peroxo Species,” J. Am. Chem. Soc. 2013 135, , 5631-5640 (DOI: 10.1021/ja311166u). Highlighted on a JACS/IC virtual issue as “a significant recent publication.”

 

Coggins, M. K.; Martin-Diaconescu, V.; DeBeer, S.; Kovacs, J. A. “Correlation Between Structural, Spectroscopic, and Reactivity Properties Within a Series of Structurally Analogous Metastable Manganese(III)-Alkylperoxo Complexes,” J. Am. Chem. Soc. 2013, 135, 4260-4272. DOI: 10.1021/ja308915x

 

Coggins, M. K.; Toledo, S.; Shaffer, E.; Kaminsky, W.; Shearer, J.; Kovacs, J. A. “Characterization and Dioxygen Reactivity of a New Series of Coordinatively Unsaturated Thiolate-Ligated Manganese(II) Complexes,”  Inorg. Chem. 2012, 51, 6633-6644.

 

Coggins, M. K.; *Kovacs, J. A. “Structural and Spectroscopic Characterization of Metastable Thiolate-Ligated Manganese(III)-Alkylperoxo Species,” J. Am. Chem. Soc. 2011, 133, 12470-12473.  DOI: 10.1021/ja205520u


Swartz, R. D.; Coggins, M. K.; Kaminsky, W.; *Kovacs, J. A. “Nitrile Hydration by Thiolate– and Alkoxide–Ligated Co-NHase Analogues.  Isolation of Co(III)-Amidate and Co(III)–Iminol Intermediates,” J. Am. Chem. Soc. 2011, 133, 3954-3963.  DOI: 10.1021/ja108749f


Villar-Acevedo, G.; Nam, E.; Fitch, S.; Benedict, J.; Freudenthal, J.; Kaminsky, W.; *Kovacs, J. A. “Influence of Thiolate Ligands on Reductive N–O Bond Activation. Probing the O2– Binding Site of a Biomimetic SOR Analogue, and Examining the Proton-Dependent Reduction of Nitrite,” J. Am. Chem. Soc. 2011, 133, 1419-1427.  Highlighted on “JACS Select” website as a “recent significant publication.”  DOI: 10.1021/ja107551u


Sun, N.; Dey, A.; Villar-Acevedo, G.;  *Kovacs, J. A. *Darensbourg, M. Y.; *Hodgson, K. O.; *Hedman, B.; *Solomon, E. I. “S K-edge XAS and DFT Studies of High and Low Spin {FeNO}7 Thiolate Complexes: Exchange Stabilization of Electron Delocalization in {FeNO}7 and {FeO2}8,” Inorg. Chem. 2011, 50, 427-436.  DOI: 10.1021/ic1006378


Nam, E.; Alokolaro, P. E.; Swartz, R. D.; Gleaves, M. C.; Pikul, J. and *Kovacs, J. A. “An Investigation of the Mechanism of Formation of a Thiolate-Ligated Fe(III)-OOH,” Inorg. Chem. 2011, 50, 1592-1602.  DOI: 10.1021/ic101776m


Lugo-Mas,P.; Taylor, W.; Schweitzer, W.; Theisen, R. M.; Xu, L.; Shearer, J.; Swartz, R. D.; Gleaves, M. C.; DiPasquale, A.; Kaminsky, W.; and *Kovacs, J. A. “Properties of Square-Pyramidal Alkyl-Thiolate Fe(III)-Complexes, Including an Analogue of the Unmodified Form of Nitrile Hydratase,” Inorg. Chem. 2008, 47, 11228 – 11236.  DOI: 10.1021/ic801704n


Kovacs, J. A.; Brines, L. M. “Understanding How the Cysteinate Contributes to the Function of the Non–Heme Iron Enzyme Superoxide Reductase,” Acc. Chem. Res. 2007, 40, 501-509.  DOI: 10.1021/ar600059h


Kitagawa, T.; Dey, A.; Lugo-Mas, P.; *Solomon, E. I.; *Kovacs, J. A. “A Functional Model for the Cysteinate–Ligated Non-Heme Iron Enzyme Superoxide Reductase (SOR),” J. Am. Chem. Soc. 2006, 128, 14448-14449.  DOI: 10.1021/ja064870d


Lugo-Mas, P.; Dey, A.; Xu, L.; Davin, S. D.; Benedict, J.; Kaminsky, W.; *Hodgson, K. O.; *Hedman, B.; *Solomon, E. I.; *Kovacs, J. A. “How Does Single Oxygen Atom Addition Affect the Properties of an Fe-Nitrile Hydratase Analogue? The Compensatory Role of the Unmodified Thiolate,” J. Am. Chem. Soc. 2006, 128, 11211-11221.


*Kovacs, J. A. "Dioxygen Activation by Non–Heme Fe–Enzymes"; Science, 2003, 299, 1024–1025.  DOI: 10.1126/science.1081792

 

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Awards & Activities

Plenary speaker, International Conference on Biological Inorganic Chemistry (ICBIC15), 2011

Saunders Endowed Lectureship, 2011 Editorial Advisory Board of Inorganic Chemistry; 2009-2012

Elected Executive Committee Member at Large, ACS Division of Inorganic Chemistry (2012– present)

Editorial Board of "BioInorganic Reaction Mechanisms" (2010–present)

Chair, “Metals in Biology” Gordon Research Conference, 2008

Council member of the Society for Biological Inorganic Chemistry, 2008-2012

Chair of the Bioinorganic subdivision of the ACS Division of Inorganic Chemistry, 2007

Organizer and Chair of “Non–Heme Iron Chemistry in Biology” Symposium, 227th ACS meeting

Organizer of the first Ronald Breslow Award Symposium, 225th ACS meeting

Ad Hoc Member of NIH Macromolecular Structure and Function (MSF-A) Study Section, 2005

Member of NIH Metallobiochemistry (BMT) Study Section 1996–1999

UC President’s Postdoctoral Fellowship

 

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