Date of Award

5-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Chemistry

Advisor

Marcus, R. Kenneth

Committee Member

Brumaghim , Julia L

Committee Member

Chumanov , George

Committee Member

Christensen , Ken

Abstract

Metallomics is a growing field of interdisciplinary research that investigates metals in biological and environmental systems. One of the major problems in detecting metals in biological systems is the instrumentation required to analyze these complex biological samples. Typically, an inductively coupled plasma-optical emission spectrometer or -mass spectrometer (ICP - OES or - MS) is used for elemental analysis and an electrospray ionization-mass spectrometer (ESI-MS) is used for molecular information. In almost all cases, the sample introduction matrix is different for each instrument, which can affect the physiological conditions of the sample and change its properties. Particle beam/hollow cathode-optical emission spectroscopy (PB/HC-OES) and liquid chromatography-particle beam/glow discharge mass spectrometry (LC-PB/GDMS) are presented as tools for obtaining both elemental and molecular species information without changing sample preparation.
The PB/HC system was coupled to a high resolution Jobin-Yvon polychromator and optimized with respect to operational parameters using a metal mixture of Ag, Ni, and Pb to display the ability of the PB/HC-OES system as a simultaneous multiple element detector. Additionally, a commercially available Hewlett Packard 5973 gas chromatography-mass spectrometer (GC-MS) was converted to a LC-PB/GDMS capable of providing comprehensive speciation (both atomic and molecular) information.
The PB/HC-OES method is presented as a tool for determining metal binding characteristics involving Tf. Transferrin (Tf) is an iron transport protein that is essential for cellular survival, providing Fe3+ to cells via receptor mediated endocytosis. Transferrin is ~ 40 % Fe3+-loaded, leaving roughly 60 % of Tf with free binding sites that can potentially bind other metal ions. Validation of the PB/HC-OES method for quantitative analysis was provided by comparing loading percentages of Fe3+ into apo-Tf with UV-VIS absorbance measurements. The PB/HC-OES method was used to determine metal loading of Ni2+ and Zn2+ into the C- and N-lobes of apo-Tf and binding of Ag+ to the surface methionines of Tf. The monitoring of Cr3+ loading into apo-Tf by PB/HC-OES and ICP-OES/UV-VIS absorbance methods are presented as further validation for the use of the PB/HC-OES method. Finally, the PB/HC-OES method was used to monitor the direct metal (Fe3+, Cr3+, and Ni2+) competition for transferrin binding under physiological relevant concentrations.

Included in

Chemistry Commons

Share

COinS