Hemoglobin is on oxygen carrying pigment, which is present in Red blood cells.It consists of two parts Heam which is the prosthetic part attached to protein called globin protein.
Heme is an Iron (Fe) porphyrin, which is composed of four pyrol rings and centrally attached iron atom in the form of ferrous ion (Fe+2).
Globin is composed of four polypeptide chains.Two of these four chains are alpha chains and two are beta chains.Alpha chains contain 141 amino acids and Four globins and four heme makes one molecule of haemoglobin.
Types of hemoglobin:-
There are two main types of haemoglobin.That are:
This is called hemoglobin A or Hb-A.It is present in major amount in adults.However it is not present in fetus.
It is composed of two alpha and two beta chains.
Here are some of the minor hemoglobins:
- Foetal hemoglobin (Hb-F)
- Hemogolbin A2 (Hb-A2)
- Embryonic hemoglobin
- Hemoglobin A3
- Glycosylated hemoglobin Hb-A1c
Difference between haemoglobin-A and heamoglobin-F:
Foetal haemoglobin is present and synthesyes in fetus and after birth most of it is replaced by haemoglobin major or Hb-A.Here are the common differences between Hb-A and Hb-F.
1.Amount in body:
Haemoglobin A is present in major amout almost above 90 person in normal human after birth, while foetal hemoglobin is the only hemoglobin in futus but after birth its amnout is decreased to 2 percent due to the production of Hb A.
Structure Difference between hemoglobin A and foetal hemoglobin:
Haemoglobin A is composed of two alpha and two beta chains while haemoglobin F is composed of two alpha and two gamma chains.
Action of alkali:
When Hb-A is treated with alkali is denatures while Hb-F remains stable after reacting with alkali.
Affinity for oxygen:
Foetal hemoglobin has more affinity for oxygen than Hb-A.
Dilivery power of oxygen:
Hb-A has more oxygen delivery power than Hb-F
Concentration before birth:
Before birth Hb-f is the only haemolglobin and Hb-A is absent.
Concentration at birth:
At birth Foetal hemoglobin is 15 percent while hemoglobin A is 85 percent.
Concentration after birth:
After one year of birth, foetal hemoglobin is only 2 percent while hemoglobin A is more than 90 percent.