Ribulose-1,5- bisphosphate carboxylase oxygenase (Rubisco) is the most abundant enzyme in the world. Functionally, Rubisco is involved in carboxylation and oxygenation processes of which the oxygenation process reduces carbon fixation by 60%. Rubisco is inefficient in distinguishing CO₂ from O_2, leading to defective CO₂ fixation. Rubiscos from different families show a broad spectrum of catalytic activity and CO₂ specificity. Studying the structural and kinetic details of red algal Rubisco, which is at the high end of the spectrum in terms of substrate specificity, may explain some differences between these species. Most Rubiscos from higher plants are hexadecameric. Interestingly, red algal Rubiscos have additional residues on the C terminal of the small subunit forming a narrow solvent channel compared to higher plant Rubiscos. The main objective of the project is to understand and characterize red algal Rubiscos from the seaweed Porphyra and compare the results with the green algal Rubisco from seaweed Ulva. Towards this goal Porphyra and Ulva Rubiscos have been extracted and purified. The size, shape  and the stability of these Rubiscos were measured using biophysical tools. Kinetic studies provided us with catalytic parameters such as K_cat and K_m for Porphyra and Ulva Rubiscos. To compare these results with well characterized Rubisco enzymes, spinach and R. rubrum Rubisco were also purified and characterized. Furthermore, ongoing studies will provide important details of functional similarities and differences between the various species.