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1. Saracini, Claudio. CARBON MONOXIDE AND DIOXYGEN PHOTO-RELEASE, BINDING KINETICS, AND THERMODYNAMICS IN 1:1 MONONUCLEAR AND 2:1 DINUCLEAR COPPER/DIOXYGEN COMPLEXES.

Degree: 2014, Johns Hopkins University

Enzymes where the active site contains one or more copper ions catalyze a wide range of organic substrate transformations in Nature. The structures and function of such active sites have been finely tuned by evolution to reach the point where dioxygen binding, activation, and utilization for oxidative chemistry has become finely modulated. As is overviewed in Chapter 1, it is useful to categorize the enzymes supported by two copper centers in their active sites as 'uncoupled' (i.e. in peptidylglycine -hydroxylating monooxygenase (PHM) and in dopamine -monooxygenase (DM)) or 'coupled' (i.e. in tyrosinase (Tyr) and in catechol oxidase (Co)) on the basis of the spatial proximity of the two metals in the three-dimensional matrix of the protein. This proximity has profound effects on the chemistry displayed by these two classes of enzymes. Importantly, dioxygen binding to the copper centers is the first step of the catalytic cycle in all of these systems. However, both mononuclear 1:1 and dinuclear 2:1 copper/O2 adducts forming in the enzymes have been shown to be unstable and their detection and their study has been difficult. As it is also discussed in Chapter 1, low temperature spectroscopic techniques together with synthetic model chemistry have come into play and greatly improved our understanding of the mechanistic details involved in such kinds of reactivity. In this work, laser flash-photolysis techniques in combination with copper-synthetic model chemistry have been employed to help the elucidation of fundamental physical and chemical properties of copper/O2 coordination and dynamics. One of the methods that has been successfully employed to study labile copper/dioxygen adducts is laser flash-photolysis of synthetic (L)copper(I)-CO compounds (L =ligand) in the presence of O2 in organic solvents. In Chapter 2, a flash-photolysis study of tridentate N-donor ligand-copper(I)-CO complexes is presented using such techniques. The implications of tricoordination vs. tetracoordination of copper ion on the dynamics of CO and O2 binding to the metal are discussed for these metal complexes. Tricoordinate environments are more similar in their coordination sphere with those present in the enzymes, as compared to their tetracoordinated synthetic counterparts. In Chapter 3, a new method to study copper/dioxygen binding for mononuclear copper complexes is presented. The previously employed carbon monoxide utilization to start from stable (L)copper(I)-CO complexes is bypassed, in this work, by affording direct O2 photo-release from relatively stable mononuclear copper(II)-superoxide complexes. Interestingly, a different quantum yield for O2 release was found depending on the excitation wavelength used and in collaborative efforts, this effect has been investigated by means of Time-Dependent Density Functional Theory (TD-DFT) studies. This work was further extended and presented in Chapter 4, where the same technique was employed for dinuclear 2:1 Cu/O2 synthetic adducts with a peroxo fragment bound in a side-on mode to the… Advisors/Committee Members: Karlin, Kenneth D (advisor).

Subjects/Keywords: Oxygen activation; coupled copper enzymes; uncoupled copper enzymes; mononuclear and dinuclear copper?O2 adducts; copper synthetic model chemistry; laser flash-photolysis; physical properties; transient absorption spectroscopy; carbon monoxide; dioxygen; tricoordinate; tetracoordinate; flash-and-trap method; copper(II)-superoxide; dicopper(II) peroxo; quantum yield; excitation wavelength; TD-DFT; end-on; side-on; irradiation; visible light; one-photon two-electron; oxidation; hydrogen atom abstraction; reversible; thermodynamics; kinetics; kinetic relaxation model; pseudo-first-order; second-order; rate constant; binding dynamics; tyrosinase; hemocyanin; catechol oxidase; PHM; DBM; irradiation; laser.

…overview for copper/dioxygen chemistry occurring in coupled dicopper-containing enzymes such as… …Interactions in Non-Coupled Dinuclear Copper Enzymes and in Model Compounds The first studies where… …15 3. Copper/O2 Interactions in Coupled Dicopper Enzymes and in Model Compounds In nature… …Model Compounds Abstract Copper-containing enzymes catalyze a wide variety of chemical… …x29; copper-containing enzymes, by using CO stretching frequencies as a labeling tool. The… 

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APA (6th Edition):

Saracini, C. (2014). CARBON MONOXIDE AND DIOXYGEN PHOTO-RELEASE, BINDING KINETICS, AND THERMODYNAMICS IN 1:1 MONONUCLEAR AND 2:1 DINUCLEAR COPPER/DIOXYGEN COMPLEXES. (Thesis). Johns Hopkins University. Retrieved from http://jhir.library.jhu.edu/handle/1774.2/37054

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Saracini, Claudio. “CARBON MONOXIDE AND DIOXYGEN PHOTO-RELEASE, BINDING KINETICS, AND THERMODYNAMICS IN 1:1 MONONUCLEAR AND 2:1 DINUCLEAR COPPER/DIOXYGEN COMPLEXES.” 2014. Thesis, Johns Hopkins University. Accessed March 05, 2021. http://jhir.library.jhu.edu/handle/1774.2/37054.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Saracini, Claudio. “CARBON MONOXIDE AND DIOXYGEN PHOTO-RELEASE, BINDING KINETICS, AND THERMODYNAMICS IN 1:1 MONONUCLEAR AND 2:1 DINUCLEAR COPPER/DIOXYGEN COMPLEXES.” 2014. Web. 05 Mar 2021.

Vancouver:

Saracini C. CARBON MONOXIDE AND DIOXYGEN PHOTO-RELEASE, BINDING KINETICS, AND THERMODYNAMICS IN 1:1 MONONUCLEAR AND 2:1 DINUCLEAR COPPER/DIOXYGEN COMPLEXES. [Internet] [Thesis]. Johns Hopkins University; 2014. [cited 2021 Mar 05]. Available from: http://jhir.library.jhu.edu/handle/1774.2/37054.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Saracini C. CARBON MONOXIDE AND DIOXYGEN PHOTO-RELEASE, BINDING KINETICS, AND THERMODYNAMICS IN 1:1 MONONUCLEAR AND 2:1 DINUCLEAR COPPER/DIOXYGEN COMPLEXES. [Thesis]. Johns Hopkins University; 2014. Available from: http://jhir.library.jhu.edu/handle/1774.2/37054

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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