Effect of the His, Cys, or Asp Substituent Groups on the Gas- and Solution Phase Zinc Affinities of the Acetyl-Aa₁-Aa₂-Gly₃-Pro₄-Tyr₅- His₆-Aa₇ Heptapeptides and Comparison With the His-Tag

Author

Michael Bawuah Owusu, East Texas A&M UniversityFollow

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Date of Award

Summer 8-18-2025

Abstract

Selective interaction with zinc-chelating resins is essential for efficient affinity-based purification of biomolecules. This study explores the zinc-binding properties of three novel heptapeptides—ac-Asp₁-Asp₂-Gly₃-Pro₄-Tyr₅-His₆-Asp₇, ac-Asp₁-Cys₂-Gly₃-Pro₄-Phe₅-His₆-Cys₇, and ac-His₁-His₂-Gly₃-Pro₄-Tyr₅-His₆-His₇—benchmarking them against the widely used 7×His tag and a previously established reference sequence, ac-His_{1-Cys2-Gly3-Pro4-Gly5-His6-Cys7. Ion mobility–mass spectrometry (IM-MS) and nuclear magnetic resonance (NMR) revealed that the His-rich peptide displayed the strongest affinity for the zinc resin and was readily eluted under mild acidic conditions. Conversely, the peptides containing multiple Asp residues showed weaker retention and no clear elution, likely due to steric hindrance and charge repulsion from their carboxyl groups. The reference peptide’s performance underscored the stabilizing effect of Cys in coordinating zinc ions. Collectively, the results offer insights into the design of more efficient metal-affinity tags for targeted purification workflows.}

Advisor

Laurence Angel

Subject Categories

Chemistry | Physical Sciences and Mathematics

Recommended Citation

Owusu, Michael Bawuah, "Effect of the His, Cys, or Asp Substituent Groups on the Gas- and Solution Phase Zinc Affinities of the Acetyl-Aa₁-Aa₂-Gly₃-Pro₄-Tyr₅- His₆-Aa₇ Heptapeptides and Comparison With the His-Tag" (2025). Electronic Theses & Dissertations. 1311.
https://lair.etamu.edu/etd/1311