Question

Biochemistry.

Please explain: the structure and oxygen binding mechanism of myogloblin and hemoglobin.

Answer 1

Answer=

The structure of Haemoglobin -

1.Haemoglobin is a tetramer consisting of two dimers  that binds to oxygen.Hb is the oxygen bindig protein of red blood cells & is a globular protein with quaternary structure.

2.Hb consists of 4 polypeptides : 2 identical alpha chains & 2 identical beta chains.

3.Each chain contains a heme ,so one Hb have 4 heme units.

4. Hb molecule contains hydrophobic amino acids inside & hydrophillic one on the surface.

Oxygen binding mechanism of HAemoglobin-

1.Each heme group contains an iron atom that is able to bind to one oxygen molecule.

therefore ,each Hb protein can bind four oxygen molecules.

2.when one oxygen binds to Hb ,it changes the structure of Hb,& that makes easier for oxygen to bind.

3. Additional oxygen binding further increases the affinity,resulting in third & then fourth oxygen molecule binding.

4. Almost all of the Hb is saturated with oxygen.

5. Hb exhibits cooperative binding.increased affinity is caused by a conformational change,or a structural change in the haemoglobin molecule.

Structure of Myoglobin= 1. is an iron containing protein.

2.Mb consists of only one polypetide chain.

3.consists of only one heme unit surrounded by a globular protein,containing 7 alpha helical & six non helical segments ,made up of 153 amino acids.

mechanism of oxygen binding to Mb- only 1 oxygen binds to Mb as it consists of only one heme group.