Abstract/Details

Development of chromatographic and mass spectrometric tools to study metal -interacting molecules in environmental and biological systems


2007 2007

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Abstract (summary)

The selectivity and sensitivity offered by the combination of liquid chromatography (LC) and mass spectrometry (MS) make it a powerful tool for studying the chemistry of compounds that are of environmental and biological importance. This dissertation focuses on developing LC-MS methods to study metal-interacting molecules in marine and biological systems.

In the studies of marine systems, organic ligands that bind Cu(II) in estuarine waters and molecules that are produced by the archaeon Pyrobaculum aerophilum to reduce Fe(III) to Fe(II) have been investigated. Two groups of Cu(II)-binding ligands in the Chesapeake Bay have been isolated by immobilized-metal affinity chromatography (IMAC). Reversed-phase liquid chromatography (RPLC) analyses indicate that both groups of ligands are hydrophilic in nature. Further MS analyses indicate that at least one of the ligands is made up of sulfur- and nitrogen-containing functional groups. LC-MS has also been used to isolate and characterize molecules that are produced by the archaeon Pyrobaculum aerophilum to reduce Fe(III) to Fe(II). Further characterization of these compounds by UV-Vis spectroscopy, NMR spectroscopy, and tandem MS (i.e. MS/MS) indicates that at least one of these compounds contains amide and quinone-like groups.

In the studies of biological systems, the gentle nature of electrospray ionization (ESI)-MS has been used to study metal-protein and protein-protein complexes of β-2-microglobulin (β2m), which is the protein component of the amyloid fibers that cause dialysis-related amyloidosis. MS, size-exclusion chromatography (SEC), and dynamic light scattering (DLS) analyses indicate that in the presence of Cu(II) β2m forms amyloid fibers by the building up of dimeric units. Furthermore, MS, SEC, and DLS data suggest that the hexamer is the nucleus that is required for the formation of the amyloid fibers. Taken as a whole, MS, SEC, DLS, and X-ray fluorescence data also suggest that Cu(II) is necessary to reach the hexameric state, but Cu(II) is released upon formation of the mature fibers. Finally, ESI-MS has been used to estimate the surface areas of β2m oligomers. Our surface area measurements suggest that the hexamer has a more compact structure than the dimer or tetramer, suggesting that Cu is released by the tetramer upon formation of the hexamer.

Indexing (details)


Subject
Analytical chemistry
Classification
0486: Analytical chemistry
Identifier / keyword
Pure sciences, Copper(II), Iron-reducing bacteria, Metal-interacting
Title
Development of chromatographic and mass spectrometric tools to study metal -interacting molecules in environmental and biological systems
Author
Antwi, Kwasi
Number of pages
207
Publication year
2007
Degree date
2007
School code
0118
Source
DAI-B 68/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Advisor
Vachet, Richard W.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3254959
ProQuest document ID
304846745
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304846745
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