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Spectroscopic studies of intermediat...

Carnegie Mellon University.

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Spectroscopic studies of intermediates in metalloenzymes and biomimetic complexes.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Spectroscopic studies of intermediates in metalloenzymes and biomimetic complexes./
Author:	Gunderson, William A.
Description:	179 p.
Notes:	Adviser: Michael P. Hendrich.
Contained By:	Dissertation Abstracts International70-06B.
Subject:	Chemistry, Biochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3362276
ISBN:	9781109215076

Spectroscopic studies of intermediates in metalloenzymes and biomimetic complexes.
Gunderson, William A.

Spectroscopic studies of intermediates in metalloenzymes and biomimetic complexes. - 179 p.

Adviser: Michael P. Hendrich.

Thesis (Ph.D.)--Carnegie Mellon University, 2009.

Metals are commonly found in proteins and play an essential role in the function of these metalloproteins. They are involved in many essential processes including, among others, the activation of dioxygen, nitrogen fixation, and the regulation of metal concentrations in cells. Spectroscopic techniques allow us to gain a better understanding of how these proteins function by providing a site specific probe of the metal centers. The identification and characterization of intermediates in the reaction cycles of catalytic proteins provides valuable information about the reaction mechanism. In addition, studies of biomimetic complexes provide another method to study the active sites of proteins, which is often complicated due to difficulties in isolation and purification. This thesis reports on the studies of a number of manganese and iron containing metalloproteins and inorganic complexes. First, the catalytic cycle of a manganese dioxygenase, MnHPCD, is explored during the reaction with its substrate and O2. Using rapid freeze quench techniques and EPR spectroscopy two intermediates in the enzymatic cycle have been identified and characterized. The first intermediate, a MnIII-superoxide speices, is the first step in the activation of O2. The decay of the second intermediate, MnII-alkylperoxo, represents the rate limiting step in the reaction. Next, the reaction of a MnII inorganic complex with peroxide was studied. The reaction forms a Mn III-peroxo species, which has been characterized with EPR spectroscopy. FeIII-TAMLs carry out oxidation reactions by activating H 2O2. The reaction of FeIII-TAML and H 2O2 was explored and a new species was identified and characterized with EPR and Mossbauer spectroscopies. The new species was identified as a mixed-valent FeIIIFeIV species with a micro-hydroxo bridging ligand. This complex was not found to be kinetically competent. Metalloregulatory proteins are involved in metal ion homeostasis to maintain required levels of essential metals or to remove toxic metals from cells. The manganese transport regulator (MntR) binds DNA in the presence of metal ions to repress the transcription of MntH, a manganese transporter. Using EPR spectroscopy the binuclear active site has been characterized and the metal binding affinity was determined. Mn titrations found that the binding of the two metals occurs in a cooperative mechanism with a binding affinity of 160 microM. Next, spectroscopic studies of Fe complexes designed to explore the feasibility of FeI and FeIV oxidation states in a Chatt-type reaction are presented. Several related complexes have been characterized with EPR, Mossbauer, and magnetization studies. Of particular interest are an FeIV&equiv;N and an FeI 2(micro-N2) complex. Finally, the design and construction of a Q-Band EPR spectrometer, operating with both perpendicular- and parallel-orientations of the magnetic fields, is presented.

ISBN: 9781109215076Subjects--Topical Terms:

1017722
Chemistry, Biochemistry.

Spectroscopic studies of intermediates in metalloenzymes and biomimetic complexes.
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100 1 $a Gunderson, William A. $3 1043634
245 1 0 $a Spectroscopic studies of intermediates in metalloenzymes and biomimetic complexes.
300 $a 179 p.
500 $a Adviser: Michael P. Hendrich.
500 $a Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: .
502 $a Thesis (Ph.D.)--Carnegie Mellon University, 2009.
520 $a Metals are commonly found in proteins and play an essential role in the function of these metalloproteins. They are involved in many essential processes including, among others, the activation of dioxygen, nitrogen fixation, and the regulation of metal concentrations in cells. Spectroscopic techniques allow us to gain a better understanding of how these proteins function by providing a site specific probe of the metal centers. The identification and characterization of intermediates in the reaction cycles of catalytic proteins provides valuable information about the reaction mechanism. In addition, studies of biomimetic complexes provide another method to study the active sites of proteins, which is often complicated due to difficulties in isolation and purification. This thesis reports on the studies of a number of manganese and iron containing metalloproteins and inorganic complexes. First, the catalytic cycle of a manganese dioxygenase, MnHPCD, is explored during the reaction with its substrate and O2. Using rapid freeze quench techniques and EPR spectroscopy two intermediates in the enzymatic cycle have been identified and characterized. The first intermediate, a MnIII-superoxide speices, is the first step in the activation of O2. The decay of the second intermediate, MnII-alkylperoxo, represents the rate limiting step in the reaction. Next, the reaction of a MnII inorganic complex with peroxide was studied. The reaction forms a Mn III-peroxo species, which has been characterized with EPR spectroscopy. FeIII-TAMLs carry out oxidation reactions by activating H 2O2. The reaction of FeIII-TAML and H 2O2 was explored and a new species was identified and characterized with EPR and Mossbauer spectroscopies. The new species was identified as a mixed-valent FeIIIFeIV species with a micro-hydroxo bridging ligand. This complex was not found to be kinetically competent. Metalloregulatory proteins are involved in metal ion homeostasis to maintain required levels of essential metals or to remove toxic metals from cells. The manganese transport regulator (MntR) binds DNA in the presence of metal ions to repress the transcription of MntH, a manganese transporter. Using EPR spectroscopy the binuclear active site has been characterized and the metal binding affinity was determined. Mn titrations found that the binding of the two metals occurs in a cooperative mechanism with a binding affinity of 160 microM. Next, spectroscopic studies of Fe complexes designed to explore the feasibility of FeI and FeIV oxidation states in a Chatt-type reaction are presented. Several related complexes have been characterized with EPR, Mossbauer, and magnetization studies. Of particular interest are an FeIV&equiv;N and an FeI 2(micro-N2) complex. Finally, the design and construction of a Q-Band EPR spectrometer, operating with both perpendicular- and parallel-orientations of the magnetic fields, is presented.
590 $a School code: 0041.
650 4 $a Chemistry, Biochemistry. $3 1017722
650 4 $a Chemistry, Inorganic. $3 517253
650 4 $a Chemistry, Physical. $3 560527
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690 $a 0488
690 $a 0494
710 2 $a Carnegie Mellon University. $3 1018096
773 0 $t Dissertation Abstracts International $g 70-06B.
790 $a 0041
790 1 0 $a Hendrich, Michael P., $e advisor
791 $a Ph.D.
792 $a 2009
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3362276