UC Davis

Enzymes, which act as catalysts for specific bioreactions under unique conditions, are valuable biological macromolecules that were originally found in living organisms. With the changing environment, some organisms have evolved differently to adapt to new environment conditions. However, not all organisms can overcome environmental stress, which results in the loss of enzyme activity. Thus, in this thesis, I first study soluble starch synthase I in wheat, which is largely affected by global climate change and causes a worldwide reduction in wheat yield. The first chapter characterizes the thermostability of 18 soluble starch synthase I enzymes from different crops, and through a thermal inactivation assay, identifies a more thermostable soluble starch synthase I compared to wheat. The results of this chapter can be applied for future genome editing to improve starch yield in wheat under high-temperature conditions. In addition, exploring the application of enzymes and applying it to our daily lives could largely be beneficial to humans’ daily applications. Many enzymes have been used in manufacturing for production or biodegradation. Therefore, the second chapter explores the application of carboxylic acid reductase and aldehyde-deformylating oxygenase in the biodegradation of perfluorooctanoic acid. The substrate promiscuity of carboxylic acid reductase was studied by measuring its kinetic parameters against different substrates.