Hemoglobin
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Haemoglobin (also spelled Hemoglobin and abbreviated Hb or Hgb) is a respiratory pigment, which transports oxygen essential for cellular metabolism.
In its quarternary structure is a globular protein, its chains are closely coiled together to form a compact, almost spherical molecule. A single molecule consists of 4 subunits: two α-polypeptide chains (each identical and containing 141 amino acids) and two β-polypeptide chains (each identical and containing 146 amino acids). The location of the genes for both types of polypeptide chains differs: α-chain gene is located on chromosome 16, the β-chain gene is located on chromosome 11. [1]
Each polypeptide is associated with haem, which is the prostatic group that mediates reversible binding of oxygen by haemoglobin. It contains a ferrous (Fe2+) ino. Each Fe2+ ion can combine with a single oxygen molecule (O2), making a total of four oxygen molecules that can be carried to the tissues and return carbon dioxide (CO2) from the tissue to the lungs.[2]
The cell that produces haemoglobin is called an erythrocte (also known as RBC, red blood cell). Each red cell contains about 280 million molecules of haemoglobin.[3]
References:
- ↑ Klug William S., Essentials of genetics, 8th edition, 2013, Boston: Pearson, p.376-377
- ↑ [Anon]. 2002. Hemoglobin synthesis [Online]. [Accessed 21.11.2014] Available from: http://sickle.bwh.harvard.edu/hbsynthesis.html
- ↑ Sears, Duane W. 1999. Overview of Hemoglobin's Structure/Function Relationships. [Online]. [Accessed 20.11.2014] Available from: http://mcdb-webarchive.mcdb.ucsb.edu/sears/biochemistry/tw-hbn/hba-overview.htm#Top