Coupled binuclear copper centers are found in a variety of different proteins and enzymes involved in the binding, activation and multielectron reduction of dioxygen to water. These include the hemocyanins, tyrosinases and the multicopper oxidases. In the multicopper oxidases, the coupled binuclear center has been determined to be part of a trinuclear copper cluster site which is the minimum structural unit required for O2 reduction. These centers exhibit unique spectral features compared to most small molecule copper complexes. The general goals of this research program have been to understand the origin of these spectral features in terms of geometric and electronic structure, to define differences in geometric and electronic structure which correlate with differences; in function and to evaluate electronic structural contributions to the reactivity of these sites in biology. It is becoming clear that these unique spectral features reflect novel active site electronic structures which can make significant contributions to catalysis. A combination of spectral and theoretical methods are applied to the study of native and perturbed protein sites and to inorganic complexes which model specific features of the active site.
The specific aims of this proposal are to: l )Complete the experimental and theoretical description of the electronic structure of the oxyhemocyanin/oxytyrosinase site and to define quantitative differences over the arthropod and mollusc hemocyanins and tyrosinase which correlate to differences in reactivity. 2)Define the electronic structure of the end-on bound hydroperoxo-Cu(II) complex which is a model for the peroxide level intermediate in the multicopper oxidases in order to determine electronic contributions which promote the irreversible reduction of peroxide to water. 3)Extend chemical and spectral studies of fungal tyrosinase to the mammalian enzyme and its interaction with substrate, and define active site perturbations caused by mutations associated with tyrosinase related oculocutaneous albinism. 4)Define active site and oxygen intermediate differences between tyrosinase and the non-coupled binuclear copper enzyme dopamine beta- hydroxylase which catalyzes the conversion of dopamine to the neurotransmitter and hormone noradrenalin. 5)Define the geometric and electronic structure of the two intermediates present in the four electron reduction of O2 to H2O in the multicopper oxidases to obtain molecular level insight into the catalytic mechanism. 6)Correlate detailed spectral studies on the trinuclear copper cluster site in laccase to the crystallographically defined trinuclear site in ascorbate oxidase, and extend these spectral studies to the trinuclear cluster sites which may be present in ceruloplasmin and copper methane monooxygenase. 7)Define the metal-ligand bonding interactions with the approximate 12.5 Angstrom electron transfer pathway (Cys-His) connecting the blue copper and the trinuclear copper centers in the multi-copper oxidases and determine the allosteric interactions between these centers and their effects on intramolecular electron transfer. 8)Extend these studies to ceruloplasmin which plays a key role in copper and iron metabolism, to define the function of the additional coppers present, the interaction with substrate, and the nature and significance of the very large intersite interactions present in this multicenter enzyme.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
2R37DK031450-14
Application #
2138634
Study Section
Metallobiochemistry Study Section (BMT)
Project Start
1982-01-01
Project End
1999-08-31
Budget Start
1994-09-01
Budget End
1995-08-31
Support Year
14
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Stanford University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Bhadra, Mayukh; Lee, Jung Yoon C; Cowley, Ryan E et al. (2018) Intramolecular Hydrogen Bonding Enhances Stability and Reactivity of Mononuclear Cupric Superoxide Complexes. J Am Chem Soc 140:9042-9045
Johnston, Esther M; Carreira, Cíntia; Dell'Acqua, Simone et al. (2017) Spectroscopic Definition of the CuZ° Intermediate in Turnover of Nitrous Oxide Reductase and Molecular Insight into the Catalytic Mechanism. J Am Chem Soc 139:4462-4476
Garcia-Bosch, Isaac; Cowley, Ryan E; Díaz, Daniel E et al. (2017) Substrate and Lewis Acid Coordination Promote O-O Bond Cleavage of an Unreactive L2CuII2(O22-) Species to Form L2CuIII2(O)2 Cores with Enhanced Oxidative Reactivity. J Am Chem Soc 139:3186-3195
Adam, Suzanne M; Garcia-Bosch, Isaac; Schaefer, Andrew W et al. (2017) Critical Aspects of Heme-Peroxo-Cu Complex Structure and Nature of Proton Source Dictate Metal-O(peroxo) Breakage versus Reductive O-O Cleavage Chemistry. J Am Chem Soc 139:472-481
Schaefer, Andrew W; Kieber-Emmons, Matthew T; Adam, Suzanne M et al. (2017) Phenol-Induced O-O Bond Cleavage in a Low-Spin Heme-Peroxo-Copper Complex: Implications for O2 Reduction in Heme-Copper Oxidases. J Am Chem Soc 139:7958-7973
Solomon, Edward I (2016) Dioxygen Binding, Activation, and Reduction to H2O by Cu Enzymes. Inorg Chem 55:6364-75
Arcos-López, Trinidad; Qayyum, Munzarin; Rivillas-Acevedo, Lina et al. (2016) Spectroscopic and Theoretical Study of Cu(I) Binding to His111 in the Human Prion Protein Fragment 106-115. Inorg Chem 55:2909-22
Solomon, Edward I; Hadt, Ryan G; Snyder, Benjamin E R (2016) Activating Metal Sites for Biological Electron Transfer. Isr J Chem 56:649-659
Tian, Shiliang; Liu, Jing; Cowley, Ryan E et al. (2016) Reversible S-nitrosylation in an engineered azurin. Nat Chem 8:670-7
Garcia-Bosch, Isaac; Cowley, Ryan E; Díaz, Daniel E et al. (2016) Dioxygen Activation by a Macrocyclic Copper Complex Leads to a Cu2O2 Core with Unexpected Structure and Reactivity. Chemistry 22:5133-7

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