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Quantification of Bacterial Histidine Kinase Autophosphorylation Using a Nitrocellulose Binding Assay
Published on: January 11, 2017
Weak Acid-Base Interactions of Histidine and Cysteine Affect the Charge States, Tertiary Structure, and
Yu-Fu Lin1, Enas N Yousef1, Efren Torres1
1Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA.
Abstract:
Zinc fingers are proteins that are characterized by the coordination of zinc ions by an amino acid sequence that commonly contains two histidines and two cysteines (2His-2Cys motif). Investigations of oligopeptides that contain the 2His-2Cys motif, e.g., acetyl-His1-Cys2-Gly3-Pro4-Tyr5-His6-Cys7, have discovered they exhibit pH-dependent Zn(II) chelation and have redox activities with Cu(I/II), forming a variety of metal complexes. To further understand how these 2His-2Cys oligopeptides bind these metal ions, we have undertaken a series of ion mobility-mass spectrometry and B3LYP/LanL2DZ computational studies of structurally related heptapeptides. Starting with the sequence above, we have modified the potential His, Cys, or C-terminus binding sites and report how these changes in primary structure affect the oligopeptides positive and negative charge states, conformational structure, collision-induced breakdown energies, and how effectively Zn(II) binds to these sequences. The results show evidence that the weak acid-base properties of Cys-His are intrinsically linked and can result in an intramolecular salt-bridged network that affects the oligopeptide properties.
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