UC Berkeley

The ability to chemically modify proteins is an essential tool for many scientific fields. The attachment of synthetic compounds on the surface of proteins has led to a better understanding of cellular function, the identification of protein structure, the development of biotherapeutics, and the generation of protein-based materials. As these applications have become more advanced, there has become an increasing need for modification strategies that target a single site to produce well-defined protein conjugates. However, strategies that only modify a single location are limited in number and often require protein engineering. This work describes the development of a site-specific N-terminal modification strategy using 2-pyridinecarboxaldehyde (2PCA) derivatives. The 2PCA reaction has been shown to effectively modify a wide range of peptide and protein substrates with excellent site-specificity. Furthermore, the usefulness of this reaction has been highlighted by the development of new protein-based materials. This strategy was used to incorporate high-affinity binding proteins into polymer matrices for the detection and removal of endocrine disrupting chemicals. To further demonstrate the versatility of this reaction, it was applied to the synthesis of a well-defined targeted imaging agent by incorporating 2PCA moieties into site-selective heterobifunctional crosslinkers. Additionally, libraries of aldehydes and rationally designed 2PCA reagents have been investigated. These preliminary studies have increased our understanding of the reaction and have provided useful information for improving product yields. Overall, the simplistic setup of this protein modification reaction and its broad protein scope make this reaction a useful strategy for the development of complex protein-based materials.