The oxygen carrier leghemoglobin is a hemoprotein found in leguminous plants. In plants with nitrogen fixing bacteria (such as alfalfa or soybeans), the presence of oxygen will poison the bacterium. Leghemoglobin acts as a natural defense against oxygen toxicity by scavenging free oxygen in these systems. The protein itself is a product of both the plant and the bacterium; the apoprotein is produced by the plant and the heme by the bacterium.
