Date of Award

Spring 5-2-2018

Degree Type


Degree Name

Master of Science (MS)



First Advisor

Jun Yin

Second Advisor

Kathryn Grant

Third Advisor

Hao Xu


Ubiquitin plays a major role in many cellular processes including protein degradation. Ubiquitin attaches to a lysine group of a substrate molecule through its carboxyl terminal end, resulting in monoubiquitination and the subsequent post-translational modification of the protein. Substrate modifications are far more complex due to seven ubiquitin lysine residues which serve as acceptors for the conjugation with other ubiquitin molecules. The focus of this thesis is centered on the elucidation of ubiquitin chain formation through catalysis of E2 cascade enzymes. Here, we incorporate (Nε-L-Thiaprolyl-L-lysine) site specifically at the K11 position of ubiquitin. The incorporated protein is deprotected forming an acceptor ubiquitin molecule, which we utilize for ligation with a donor molecule to construct a di-ubiquitin probe and conjugate with a specific E2 enzyme. Future studies are aimed at retrieving a three-dimensional structure for this DiUb-E2 conjugate to understand the mechanisms of multiple proteins involved in ubiquitin chain synthesis.