Abstract/Details

The electron paramagnetic resonance characterization of ferrous nitrosyl non-heme iron models and enzymes


2010 2010

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Abstract (summary)

Non-heme iron oxygenases represent a class of enzyme that activate dioxygen and catalyze a diverse range of thermodynamically challenging reactions. Phenylalanine hydroxylase(PheH) is a non-heme Fe enzyme that catalyzes the hydroxylation of the C4 position of the phenol side chain of phenylalanine(phe) to yield tyrosine and Tyrosine hydroxylase(TyrH) catalyzes the hydroxylation of the C3 position of the phenol side chain of tyrosine(tyr) to yield L-DOPA. These two enzymes contain a highly conserved iron binding motif termed the facial triad with 2 histidine ligands and a carboxylate facially coordinating the iron. This work focuses on the EPR characterization of these two enzymes and a series of model complexes containing the same N, N, O facial binding motif. The catalytically relevant oxidation state for non-heme iron oxygenases is Fe(II) which is EPR silent, this problem was overcome by studying Fe(II)-NO complexes where the NO acts as an oxygen surrogate and couples to the Fe(II) generating an EPR active S=3/2 system. Using 2H electron spin echo envelope modulation(ESEEM) sepectroscopy we have shown that in TyrH and PheH there is a structural change that occurs in the active site upon substrate addition which results in movement of the pterin co-susbtrate closer to the Fe(II) center. 2H ESEEM has also shown that in TyrH and PheH a change in the orientation of the Fe-NO bond with respect primary substrate occurs on co-substrate binding. Hyperfine sub-level correlation spectroscopy was used to characterize the magnetic environment of the model complexes including the chelating ligand and solvent molecules. These results were applied to aid in the understanding of the HYSCORE spectra collected on TyrH and PheH.

Indexing (details)


Subject
Biochemistry;
Inorganic chemistry;
Physical chemistry
Classification
0487: Biochemistry
0488: Inorganic chemistry
0494: Physical chemistry
Identifier / keyword
Pure sciences; Ferrous nitrosyl; Non-heme iron; Tyrosine hydroxylase
Title
The electron paramagnetic resonance characterization of ferrous nitrosyl non-heme iron models and enzymes
Author
Krzyaniak, Matthew D.
Number of pages
131
Publication year
2010
Degree date
2010
School code
0128
Source
DAI-B 72/08, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9781124658834
Advisor
McCracken, John
University/institution
Michigan State University
University location
United States -- Michigan
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3458520
ProQuest document ID
871229334
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/871229334
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