Heterotrophs such as E. coli contain metabolic pathways with enzymes called carboxylases that are capable of fixing CO2 gas to form metabolites, which has implications for aiding with CO2’s role in climate change. The reductive branch of the tricarboxylic acid (TCA) cycle serves as an important pathway for NAD+ regeneration in enteric bacteria in anaerobic conditions and leads to the production of succinate, a useful industrial product. The enzyme phosphoenolpyruvate carboxykinase is responsible for fixing CO2 in the conversion of PEP to OAA within this pathway and has potential to be a significant carbon fixation module in heterotrophic organisms. This project explored pck genes from select organisms by transforming plasmids to test if these variants have improved kinetics compared to the native E. coli Pck and to investigate their ability to improve succinate bioproduction.