Metal-binding proteins are specialized proteins that can bind to metal ions, playing crucial roles in various biological processes. These proteins help transport essential metals like iron, copper, and zinc within cells and tissues, ensuring that organisms maintain proper metal homeostasis. They can also participate in enzymatic reactions, where the metal ions act as cofactors, enhancing the protein's activity. These proteins are vital for many cellular functions, including oxygen transport and electron transfer. Examples include hemoglobin, which binds iron to transport oxygen in the blood, and metallothioneins, which help detoxify excess metals. Understanding metal-binding proteins is essential for studying health and disease.