Date of Thesis

Spring 2022


Protein-protein interactions (PPIs) are involved in many cellular functions, and the misregulation of these interactions is the cause of many genetic diseases and cancers. PPIs are very specific, and therefore are an appealing target for therapeutic agents. The most common structural element found in the binding regions of PPIs is a single ɑ-helix. This allows for the possibility of using peptides as inhibitors of PPIs - a peptide can be designed which mimics the specific ɑ-helix found in a specific PPI, targeting the PPI while minimizing unwanted side effects. For this to work, it is necessary to induce secondary structure in a short peptide, which does not happen naturally. Here, we use metal ion staples to induce peptides to fold into an ɑ-helix upon metal ion binding. However, for a peptide to be useful as a therapeutic agent it is also necessary for these peptides to be able to enter a cell, to access the location where the PPI occurs. Therefore, this work aims to explore the cellular internalization of metal binding peptides, and to specifically address the role of metal ion identity, and the role of metal-induced secondary structure. First, five peptides were designed and synthesized which differ in their metal binding capabilities. The extent to which each of these peptides are able to cross the membrane of mammalian cells in the presence and absence of metal ions was measured. A cell internalization assay was optimized, and it was determined that the optimal conditions are 5 µM peptide, a 30-minute incubation time, and this should be performed in MOPS buffer. Based on the results of this study, it appears that the number of bound metal ions is a key factor in the level of internalization, and the secondary structure of the peptides is less important. This work is the foundation to determine the features that maximize the cellular internalization of a metal binding peptide, a critical step in using peptides as therapeutic agents.


Peptides, Metal-binding peptides, Cellular Internalization

Access Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science


Cell Biology/Biochemistry

First Advisor

Sarah Smith