Mononuclear non-heme iron enzymes catalyze a wide range of reactions which either involve O2 activation by a high-spin ferrous site or substrate activation by a high-spin ferric site. Recently a class of non-heme iron enzymes that has thiolate ligation has also been defined. These enzymes are directly related to genetic disorders (phenylketonuria, alkaptonuria), involved in the biosynthesis of antibiotics, lactamase inhibitors, and leukotrienes and lipoxins, important in the repair of DNA alkylation damage, and utilized in the treatment of certain cancers. Non-heme iron enzymes have generally been far more difficult to study than heme enzymes. New spectroscopic methods (emphasizing variable-temperature, variable-field magnetic circular dichroism, and metal K- and L-edge and ligand K-edge X-ray absorption spectroscopy) have been and are being developed which enable the detailed study of these enzymes. Density functional theory calculations supported by these spectroscopic data provide further insight into electronic structure and allow evaluation of reaction coordinates. The goals of this research are to: 1) directly probe the ferrous active sites and their interactions with substrate, cofactor and other relevant factors to elucidate catalytic mechanisms on a molecular level;2) understand how cosubstrate binding initiates the reaction of the ferrous center with O2;3) experimentally and theoretically understand the nature of oxygen intermediates and factors that control their reactivity;4) determine how non-heme relates to heme iron in activating O2;5) understand the nature of substrate activation by an oxidized iron center, and define the factor(s) leading to selectivity in aromatic ring cleavage;6) determine the contributions of the highly covalent thiolate S-Fe(lll) bond to the different reactivities of the cysteine liganded non-heme iron enzymes.

Public Health Relevance

The non-heme iron enzymes are associated with a wide range of diseases including arteriosclerosis, cancer (regulation of hypoxia) and neurological disorders (Alzheimer's, Parkinson's, etc.). These enzymes are also extremely important in the treatment and prevention of disease due to their roles in the biosynthesis of antibiotics (penicillins, cephalosporins, vancomycin), anti-cancer activity (Bleomycin), DNA repair and the bioremediation of pollutants (including PCBs). These studies provide a fundamental understanding of the modes of action of these enzymes enabling strategies to improve or inhibit function and enhance drug design.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM040392-23
Application #
7808775
Study Section
Special Emphasis Panel (ZRG1-BCMB-B (02))
Program Officer
Fabian, Miles
Project Start
1988-07-01
Project End
2011-04-30
Budget Start
2010-05-01
Budget End
2011-04-30
Support Year
23
Fiscal Year
2010
Total Cost
$385,834
Indirect Cost
Name
Stanford University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Srnec, Martin; Wong, Shaun D; Matthews, Megan L et al. (2016) Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2: Contributions to H Atom Abstraction Reactivity. J Am Chem Soc 138:5110-22
Solomon, Edward I; Park, Kiyoung (2016) Structure/function correlations over binuclear non-heme iron active sites. J Biol Inorg Chem 21:575-88
Light, Kenneth M; Yamanaka, Yasuaki; Odaka, Masafumi et al. (2015) Spectroscopic and Computational Studies of Nitrile Hydratase: Insights into Geometric and Electronic Structure and the Mechanism of Amide Synthesis. Chem Sci 6:6280-6294
Kroll, Thomas; Solomon, Edward I; de Groot, Frank M F (2015) Final-State Projection Method in Charge-Transfer Multiplet Calculations: An Analysis of Ti L-Edge Absorption Spectra. J Phys Chem B 119:13852-8
Hong, Seungwoo; Sutherlin, Kyle D; Park, Jiyoung et al. (2014) Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex. Nat Commun 5:5440
Pratter, Sarah M; Light, Kenneth M; Solomon, Edward I et al. (2014) The role of chloride in the mechanism of O(2) activation at the mononuclear nonheme Fe(II) center of the halogenase HctB. J Am Chem Soc 136:9385-95
Light, Kenneth M; Hangasky, John A; Knapp, Michael J et al. (2014) First- and second-sphere contributions to Fe(II) site activation by cosubstrate binding in non-heme Fe enzymes. Dalton Trans 43:1505-8
Kang, Mingchao; Light, Kenneth; Ai, Hui-Wang et al. (2014) Evolution of iron(II)-finger peptides by using a bipyridyl amino acid. Chembiochem 15:822-5
Srnec, Martin; Wong, Shaun D; Solomon, Edward I (2014) Excited state potential energy surfaces and their interactions in Fe(IV)=O active sites. Dalton Trans 43:17567-77
Kroll, Thomas; Hadt, Ryan G; Wilson, Samuel A et al. (2014) Resonant inelastic X-ray scattering on ferrous and ferric bis-imidazole porphyrin and cytochrome c: nature and role of the axial methionine-Fe bond. J Am Chem Soc 136:18087-99

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