Heme Synthesis Lab Report

Synthesis of Hb involved the co-ordinate production of heme & globin. As Hb is composed of 4 subunits i.e. two α & two β globin chain & each of this subunit consist of heme group in the center.
Heme- regulates reversible binding of oxygen by Hb.
Globin- It is a protein surrounding & protecting the heme molecule.

Heme synthesis:

Heme synthesis is carried out in mitochondria & cytosol of the cell involving cascade of steps :-

1) The first step occurs in mitochondria, where condensation of succinyl-CoA & glycine is carried out by enzyme ALA-synthase resulting in product formation i.e. 5-aminolevulinic acid.

2) 5-aminolevulinic acid is transported to the cytosol for formation of porphobilinogen molecule.

3) After formation

5) Dehydrogenation of protoporphyrin9 is the final modification step where enzyme ferrochelate inserts an iron into the ring of protoporphyrin IX producing heme.

6) Heme exits from mitochondria & further combined with the globin molecule.

There are two types of globin chain which combine to form the globin portion of Hb. One is alpha globin chain & other is non-alpha globin chain. Each of this globin chain is attached to its heme moiety.

The location & synthesis of globin chain varies right from embryonic stage to fetal stage to adult life. During various stages of life different globin chains are express this variation describes the “Types of Hb present in a human life
• Embryonic – In first week of embryogenesis, one of globin chain always remain non-alpha.
• Fetal – Fetus consist of non-alpha chain called “gamma” chain. When two α & two γ chain combine a “fetal haemoglobin” is formed i.e. Haemoglobin F. It is the 1 ͦ Hb in developing fetus.
• Adult - After birth, “beta” a different non-alpha globin chain pairs with α globin chain. The combination of 2 α chain & 2 β chain forms “adult Hb” called “Haemoglobin