Molecule of the Week

Hemoglobin

February 25, 2013

Hemoglobin, the major component of red blood cells, transports oxygen from the lungs to tissues throughout the body. It also carries some CO2 back to the lungs.

Hemoglobin consists of four units, each of which consists of a globin polypeptide chain bound to an iron-containing heme molecule. An α-chain fragment of the polypeptide L-alanyl-L-seryl-L-leucyl-L-α-aspartyl-L-lysyl-L-phenylalanyl-L-leucyl-L-alanyl-L-seryl-L-valyl-L-seryl-L-threonyl-L-valyl-L–leucine (molar mass 1450) is shown in the figure. The average molar mass of an entire mammalian hemoglobin molecule is ≈64,500.

Here are some significant events in the history of hemoglobin discovery:

  • 1825: J. F. Engelhard shows that the Fe/protein ratio is the same in several species’ hemoglobin.
  • 1840: F. L. HÜnefeld discovers that hemoglobin transports oxygen.
  • 1922: M. Heidelberger crystallizes oxygenated hemoglobin derived from horse and dog erythrocytes.
  • 1959: M. Perutz elucidates the structure of myoglobin, which is similar to hemoglobin. This accomplishment earns him a share of the 1962 Nobel Prize in Chemistry.

More about this molecule from CAS, the most authoritative and comprehensive source for chemical information.