deoxyhemóglóbín

Deoxyhemoglobin is a form of hemoglobin, the iron-containing protein in red blood cells responsible for transporting oxygen throughout the body. It exists when hemoglobin is not bound to oxygen, representing its deoxygenated state. Hemoglobin consists of four polypeptide chains—two alpha and two beta—each containing a heme group with an iron atom capable of binding oxygen reversibly.

In its deoxygenated form, deoxyhemoglobin has a distinct structure compared to its oxygenated counterpart, oxyhemoglobin. The iron atoms in the heme groups remain in the ferrous (Fe²⁺) state, but the protein’s conformation shifts slightly, reducing its affinity for oxygen. This structural change is crucial for the efficient delivery of oxygen from the lungs to tissues, where oxygen partial pressure is lower.

Deoxyhemoglobin plays a key role in the Bohr effect, where a decrease in pH or an increase in carbon dioxide levels further reduces its oxygen-binding affinity, facilitating oxygen release in metabolically active tissues. It also contributes to the characteristic dark red color of venous blood, as opposed to the brighter red hue of arterial blood rich in oxyhemoglobin.

In pathological conditions, such as carbon monoxide poisoning, hemoglobin may bind to carbon monoxide instead of oxygen, forming carboxyhemoglobin and impairing oxygen transport. While deoxyhemoglobin itself is not directly involved in these disorders, its balance with oxyhemoglobin is essential for maintaining proper respiratory function. The study of deoxyhemoglobin helps elucidate the molecular mechanisms of oxygen delivery and the physiological adaptations of hemoglobin under varying conditions.