Haemoglobin, is the iron-containing oxygen-transport metalloprotein in the red blood cells (erythrocytes) of almost all vertebrates as well as the tissues of some invertebrates. Haemoglobin in blood carries oxygen from the lungs to the rest of the body. Haemoglobin develops in cells in the bone marrow that become red blood cells. When red cells die, haemoglobin is broken up: iron is removed and transported to the bone marrow by proteins called transferrins, and used again in the production of new red blood cells.

1. FORMATION OF HAEMOGLOBIN
Haemoglobin, is the iron-containing oxygen-transport metalloprotein in the red blood
cells (erythrocytes) of almost all vertebrates as well as the tissues of some invertebrates.
Haemoglobin in blood carries oxygen from the lungs to the rest of the body.
Haemoglobin develops in cells in the bone marrow that become red blood cells. When
red cells die, haemoglobin is broken up: iron is removed and transported to the bone
marrow by proteins called transferrins, and used again in the production of new red blood
cells.

2. • Haemoglobin is a protein made up of four polypeptide chains (α1, α2, β1, and β2).
• Each chain is attached to a heme group composed of porphyrin (an organic ring
like compound) attached to an iron atom.
• These iron-porphyrin complexes coordinate oxygen molecules reversibly, an ability
directly related to the role of haemoglobin in oxygen transport in the blood.
 Haemoglobin (Hb) is synthesized in a complex series of steps.
• The heme part is synthesized in a series of steps in the mitochondria and
the cytosol of immature red blood cells, while the globin protein parts are
synthesized by ribosomes in the cytosol.
• Production of Hb continues in the cell throughout its early development from
the proerythroblast to the reticulocyte in the bone marrow.

3. • Haemoglobin synthesis is a complicated process. This takes place in the red blood cells.
– Amino acids are assembled in the ribosomes and give rise to α2 β2 globulin.
– Heme molecule will have protoporphyrin by the chemical combination of glycine and
succinyl CoA in the presence of Vitamin B6 and form heme.
– Transferrin gives Iron which will combine with the heme molecule.
• Heme molecule consists of protoporphyrin protein and iron (Fe++).
• Globulin consists of four polypeptide chains (α1, α2, β1, and β2).