Free divalent and trivalent metal ion

The term "Free divalent and trivalent metal ion" does not refer to a single defined molecule, receptor, or protein, but rather to a chemical category encompassing a broad range of charged metal atoms with either a +2 (divalent) or +3 (trivalent) oxidation state. Examples include Fe²⁺, Cu²⁺, Ni²⁺ (divalent) and Fe³⁺, Al³⁺, Cr³⁺ (trivalent) ions. Free ions, distinct from their protein- or chelator-bound forms, play critical roles in various physiological processes such as acting as enzyme cofactors, regulating redox status, modulating gene expression via effects on hypoxia-inducible factor (HIF) signaling, and influencing cellular metabolism and energy production[1][2]. However, excess free metal ions can be toxic, generating reactive oxygen species (ROS), inducing oxidative stress, and disrupting membrane and protein functions. The presence and homeostasis of these ions are tightly regulated in living systems; dysregulation is implicated in cellular injury, inflammation, and disease. Because "free divalent and trivalent metal ion" is a generic chemical class—not a specific biological target, receptor, or actionable drug target category—this entry should generally not be used as a canonical therapeutic target in structured pharmacological/biological databases[1][2][3].