Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation. Carboxysomes are made of polyhedral protein shells about 80 to 140 nanometres in diameter. These compartments are thought to concentrate carbon dioxide to overcome the inefficiency of RuBisCo - the predominant enzyme in carbon fixation and the rate limiting enzyme in the Calvin cycle. These organelles are found in all cyanobacteria and many chemotrophic bacteria that fix carbon dioxide. Discovery Using… (More on Carboxysome)