Development of Thioamides as Protein Probes

Daniel Miklos Szantai-Kis, University of Pennsylvania

Abstract

Thioamides have been used for various applications with small molecules and peptides, including as protease sensors, fluorescence quenching probes, folding probes, and handles for site-specific chemical modification. However, their use in proteins has been limited due to cumbersome incorporation through semi-synthesis, as well as their unknown effects on protein structure. In this work, I address these issues from multiple perspectives. I present improvements for the synthesis of thioamide-containing peptides, which are needed for semi-synthesis. I also investigate the effects that thioamide substitutions have on tertiary structure in a model protein and show that based on thermal denaturation experiments, the position of thioamide substitution can have a significant impact on the tertiary fold. Furthermore, I demonstrate a new semi-synthetic strategy to obtain mg quantities of a thioamide-containing protein that will enable structural investigation by Nuclear Magnetic Resonance spectroscopy and X-Ray crystallography. Finally, I describe my attempts at the genetic incorporation of thioamides using a combination of unnatural amino acid mutagenesis and amber suppression. While the last part was not successful, the efforts to improve semi-synthesis of thioamides will enable the use of thioamides as probes in proteins in a similar fashion as they have been used previously in peptides.

Subject Area

Cellular biology|Biochemistry|Organic chemistry

Recommended Citation

Szantai-Kis, Daniel Miklos, "Development of Thioamides as Protein Probes" (2019). Dissertations available from ProQuest. AAI13878996.
https://repository.upenn.edu/dissertations/AAI13878996

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