UCSF

In my dissertation, I present a comprehensive investigation into chitinase enzymes and their diverse roles in biology, as well as contributions to antiviral drug development and social justice initiatives. The first chapter focuses on Acidic Mammalian Chitinase (AMCase), an enzyme responsible for degrading the resilient polysaccharide chitin in mammalian stomachs and lungs. Through the development of novel chitinase activity assays, we explore the effects of asthma-associated mutations, examine the contributions of individual enzyme domains in degrading crystalline chitin, and compare the behavior of AMCase with chitotriosidase, another chitinase in mammals. Additionally, we explore the challenges of engineering hyperactive chitinases, highlighting the limitations of traditional screening methods when assessing complex chitin substrates.In the second chapter, I focus on the SARS-CoV-2 macrodomain (Mac1), a viral protein that antagonizes host antiviral signaling. Using computational and structural techniques, we identify numerous small molecules that bind to the active site of the macrodomain, providing a foundation for the development of potent SARS-CoV-2 macrodomain inhibitors. We validate these findings through solution binding assays, utilizing multiple biophysical techniques to confirm fragment hits. In the third chapter, I delve into the catalytic mechanism underlying the pH-dependent activity profile of mouse Acidic Mammalian Chitinase (mAMCase). By employing a combination of biochemical, structural, and computational modeling approaches, I uncovered the ability of the mouse homolog to function effectively in both acidic and neutral environments. I determined the kinetic properties of mAMCase across a broad pH range and reveal its intriguing dual activity optima at pH 2 and 7. Through high-resolution crystal structures of mAMCase bound to chitin, I unveiled extensive conformational ligand heterogeneity, providing valuable insights into the catalytic mechanism of mAMCase. These results integrate structural, biochemical, and computational approaches to deliver a more complete understanding of the catalytic mechanism governing mAMCase activity at different pH. In the fourth chapter, I outline my contributions to advancing diversity, equity, inclusion, and justice (DEIJ) at UCSF, other academic institutions, and beyond academia. This chapter not only recounts my experiences cultivating LGBTQ+ community, advocating for racial justice, and interrogating institutional policies regarding graduate admissions, but also renders visible otherwise neglected contributions to improving the social conditions in which we perform science.