Haemoglobin pigments

April 26, 2022

Hemoglobin is a protein in red blood cells (RBCs).

It plays a vital role in your body. It carries oxygen from your lungs to your tissues and organs.

It is a conjugated protein, & Chromoprotein.

It is a chromoprotein forming 95% of dry weight of RBC and 30% to 34% of wet weight.

It is made up of Iron (haem) and Protein (globin).

It also acts as a buffer and its molecular weight is 68,000.

Its function is to carry the respiratory gases, oxygen and carbon dioxide.

Hemoglobin is made up of four amino acid chains. Amino acids are the building blocks of proteins.

Each of these chains contains heme. This is a compound that contains iron. One of the functions of heme is to transport oxygen in the bloodstream.

Hemoglobin is what gives RBCs their shape. RBCs usually look like donuts, but with a thin center instead of a hole.

Some conditions like sickle cell anemia can cause abnormally shaped RBCs. This can lead to serious health problems.

What is the pigment in hemoglobin?

Hemoglobin itself is a compound of a colorless protein, globin, and an iron porphyrin pigment.

Structure of Hemoglobin

Iron containing pigment called Haem attached with protein – Globin.

Haeme is Iron – porphyrin complex called IRON- PROTOPORPHYRIN IX.

Globin – Protein.

Structure of Haem

IRON

IRON - Ferrous form (Fe2+).

Iron attached to nitrogen atom of each pyrrole ring.

On iron loose bond for:

- Oxygen

- Carbon monoxide.

Porphyrin nucleus.

4 Pyrrole Rings (Tetrapyrrole)

Bridges – Methine (CH)

Side chains – 8

- Methyl (CH3) - 4

- Vinyl (CH.CH2) - 2

- Propionic acid - 2 (CH2.CH2.COOH)

It is present in the Ferrous (Fe2+) form. It is in unstable or loose form. In some abnormal condition it is in Ferric (Fe3+) state which is a stable form.

Porphyrin – The pigment part of the heme is called porphyrin. It is formed by the pyrrole ring. These pyrrole rings are attached to one another by methane (CH4) bridges.