Metal-mediated ligand affinity chemistry

University Of Kentucky Research Foundation, Lexington KY

Investigators

Abstract

With the support of the Chemistry of Life Processes (CLP) Program in the Division of Chemistry, Samuel G. Awuah of the University of Kentucky (UK) is developing new chemical tools to study protein function. Chemical reagents that modify peptides and proteins have led to a wide variety of biomolecule conjugates that has accelerated our understanding of protein function and the development of improved therapeutics. Despite the advancement, inherent limitations of current methods make new chemical tools a necessity for protein chemical modification and biomolecule manipulation particularly within their native sites in cells or whole animals. The Awuah research team will apply a combination of synthetic chemistry and molecular biology to study reactions of specific amino acids with metal-based compounds towards protein modulation. If successful, this study will establish fundamental principles that have potential long-term impact for elucidating complex biological pathways and protein-protein interactions as well as the design of therapeutics and biocatalysts. The project has the potential to develop biocompatible metal-mediated reactions that transfer desirable ligands to intended biological locations irreversibly, thusly providing a potentially useful tool for scientists across disciplines. Undergraduate students including those of underrepresented in the STEM (science, technology, engineering and mathematics) fields are to be introduced to interdisciplinary science at the interface of inorganic, organic, biological, and analytical chemistry, to build their confidence and scientific abilities in an interdisciplinary, discovery-based manner. The ultimate long-term goal is to greatly leverage the resources at UK to increase the participation and retention of diverse student groups in STEM fields.  Significant efforts are underway to design site-selective chemical conjugation of synthetic molecules to expand the functional and therapeutic capacity of proteins. The chemical modification of natural amino acids in peptides and proteins including protein-protein interactions (PPIs) has proved challenging due to the use of a bioorthogonally-labeled partner restricted to the N- or C-terminus or the need for extensive sequence engineering. Importantly, the reactions employed in site-selective protein conjugation need to be chemoselective, regioselective, and operational under mild, physiologically relevant conditions. This project aims to develop metal-mediated cysteine and lysine arylation as an elaborate tool for bioconjugation, and to utilize this tool to explore structure-function relationships on select peptides and proteins to establish the intracellular target potential of this S- and N-arylation strategy. The aims of the proposed work are to investigate cysteine/lysine arylation with gold-based reagents; to conduct structure-function studies on proteins and to explore lysine reactivity and ligandability within the human proteome. If successful, the studies being undertaken in this project could provide critical solutions to longstanding problems in chemical biology by introducing powerful methods to selectively modify peptides and proteins within their native sites. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.