syrebindarna

Syrebindarna, or the oxygen binders, are a group of proteins and other molecules that reversibly bind molecular oxygen to enable its transport, storage, or delivery within living organisms. The best known examples are vertebrate hemoglobin, which carries oxygen in blood, and myoglobin, which stores it in muscle tissue. Other oxygen carriers include hemocyanin and hemerythrin in some invertebrates, as well as various bacterial and archaeal globin-like proteins.

In vertebrates, hemoglobin is a tetramer composed of two alpha and two beta (or gamma in fetal development) subunits, each containing a heme group with iron that binds O2. Oxygen binding is cooperative, so binding to one subunit increases affinity in the others, enabling uptake in the lungs and release in tissues. Myoglobin is a monomer with higher oxygen affinity, providing intracellular storage and aiding diffusion within muscle.

Affinity is modulated by pH, carbon dioxide, temperature, and organic phosphates such as 2,3-bisphosphoglycerate (2,3-BPG). The Bohr effect lowers hemoglobin’s affinity in tissues, while adaptations at high altitude modify oxygen affinity. Abnormalities, such as methemoglobinemia, can impair oxygen transport.

Globin genes diversified through evolution, giving rise to multiple oxygen-binding proteins across lineages. Fetal hemoglobin (HbF) and others differ in subunit composition and oxygen affinity, supporting efficient maternal-to-fetal transfer.

Studying syrebindarna informs physiology, medicine, and biotechnology, including blood substitutes and therapies for anemia or hypoxia-related conditions.