Oxyhemoglobin (HbO2) (HbO2)

Oxyhemoglobin is the oxygenated form of hemoglobin, the iron-containing metalloprotein in red blood cells responsible for transporting oxygen from the lungs to peripheral tissues (StatPearls, 2023). Each hemoglobin molecule is a tetramer that can bind up to four oxygen molecules at its heme groups, transitioning from a low-affinity T-state (deoxyhemoglobin) to a high-affinity R-state (oxyhemoglobin) through cooperative binding (UniProt P69905). This reversible process is critical for maintaining cellular respiration and systemic metabolism. In sickle cell disease, stabilizing oxyhemoglobin is a key therapeutic strategy because the oxygenated form of sickle hemoglobin (HbS) does not polymerize, thereby preventing red blood cell sickling and subsequent vaso-occlusive crises (Vichinsky et al., 2019). Drugs like voxelotor act as allosteric modulators to increase hemoglobin's affinity for oxygen, effectively increasing the proportion of oxyhemoglobin in the blood (FDA, 2019). However, pathological states such as carbon monoxide poisoning or methemoglobinemia can interfere with this binding, leading to life-threatening hypoxia (Mayo Clinic, 2023).

Other names

Oxygenated hemoglobinHemoglobin-oxygen complexR-state hemoglobinOxy-Hb

Allosteric modulation of hemoglobin to increase its affinity for oxygen, thereby stabilizing the relaxed (R) state and preventing the polymerization of deoxygenated sickle hemoglobin (Vichinsky et al., 2019).