Metalloproteins are proteins that contain metal ions as part of their structure. These metal ions, such as iron, copper, or zinc, play crucial roles in the protein's function, often participating in processes like electron transfer, catalysis, and oxygen transport. Hemoglobin, for example, is a metalloprotein that carries oxygen in the blood, utilizing iron to bind oxygen molecules. The presence of metal ions can significantly influence the protein's stability and activity. Metalloproteins are found in various biological systems, including enzymes, transport proteins, and structural proteins. Their diverse functions make them essential for many physiological processes in living organisms.