UCSF

Bio-conjugation and protein engineering are two powerful biochemical methods to alter proteins to have enhanced functions. Bio-conjugation allows for proteins to be attached to other protein and non-protein molecules in ways that would never appear naturally in the biological world, bestowing new properties onto a protein. Protein engineering allows for manipulation of the linear amino-acid sequence of a protein to alter its biochemical properties. These types of substitutions can change the way a protein folds, how it interacts with partner proteins, and its own chemical reactivity. These methods are currently highly utilized in the development of novel therapeutics and research tools. For both methods, location is one of the most important considerations for successful applications. Years of bio-conjugation research has revealed that attachment at a controlled and known site improves the reproducibility and properties of a given conjugate. In protein engineering, not all sites on a protein have the same chemical environment and thus even the same amino acid at a different location may react differently. Thus, even with these powerful biochemical methods, careful research must be done to determine the optimal attachment method, mutation location, and site. However, the optimized conjugate or engineered protein has great potential as a novel therapeutic, diagnostic, or research tool. Here, I describe three approaches using bio-conjugation and protein engineering to develop novel and optimized protein conjugates or engineered protein fusions for various applications. In Chapter 1, I describe the use of a methionine-based conjugation method to attach cytotoxic cancer drugs on antibodies as selective drug delivery carriers. In Chapter 2, I highlight the development of rapid, facile protein biosensors to detect antibodies to COVID-19. In Chapter 3, I describe the development of an improved cell-surface biotinylation method utilizing novel enzyme conjugates.