pH Dependent Chelation Study of a Series of Modified Hexapepetides with Zn(II), Ni(II), and Co(II) Using Electrospray Ionization-Ion Mobility Mass Spectrometry

Document Type


Degree Name

Master of Science (MS)



Date of Award

Fall 2020


Previous studies performed on an alternative metal-binding peptide (amb1A) which possess a 2His-2Cys motif in its primary structure prompted the design of a series of modified hexapeptides. Replacement of the His and Cys potential binding sites with Gly as well as amidation of the C-terminus was adopted. These modifications mirrored variations to a series of heptapeptides with a Tyr amino acid residue that has been published. This study investigated the effectiveness of the 2His-2Cys motif to pH-dependent Zinc(II), Nickel(II), and Cobalt(II) metal ion binding to the hexapeptides. It also provided insights into the influence of a lack of Tyr residue on metal chelation in the peptides studied in this work. Qualitative and quantitative analysis of species of interest were carried out through the use of the electrospray ionization – ion mobility – mass spectrometry (ESI-IM-MS) which allowed for the native state study of ions in the gas-phase. Results indicated pH-dependent metal chelation over pH 7.0-9.4 as well as specificity for metal binding by select peptides. Structural changes to the peptides were also evident due to the correlation of both experimental and theoretical collision cross sections.


Laurence A. Angel

Subject Categories

Chemistry | Physical Sciences and Mathematics