Comparative Study of Metal Ion Labeling of the Conformational and Charge States of Native and Disulfide Reduced Lysozyme

Document Type


Degree Name

Master of Science (MS)



Date of Award

Summer 2013


The research investigates the metal ion labeling of various conformational and charge states of native and disulfide reduced lysozyme using divalent metal ion tags of Zn2+ and Fe2+. The study used travelling-wave ion mobility with quadrupole and orthogonal time-of-flight mass spectrometry to quantify the extent of metal ion labeling of lysozyme as a function of pH, charge state and conformation. The characterization of three-dimensional protein structure by ion mobility mass spectrometry is an area of current interest as the gas-phase conformation, in many instances, can be related to that of the solution-phase. Labeling of native and disulfide reduced lysozyme was conducted with 30-fold molar excess of Zn2+ and 30-fold molar excess of Fe2+ and collision cross sections were calculated for the various species observed. The calculated cross-sections were compared with cross sections from published X-ray crystallography and nuclear magnetic resonance spectroscopy and are found to be in good agreement with these structures. Disulfide reduced lysozyme exhibited four distinct conformational families in the gas-phase termed as the highly folded, folded, partially unfolded and unfolded. Labeling of these conformational states was observed to differ with the partially unfolded 7+charge state of lysozyme exhibiting the greatest extent of labeling.


Laurence Angel

Subject Categories

Chemistry | Physical Sciences and Mathematics