Structure of Hemoglobin Hemoglobin is a chromo protein and is found in red blood cells, it’s a conjugated protein (heme as prosthetic group + globin as the protein part apoprotein). Adults have 14.0 to 16.0 gm% of Hb and 90 mg/kg of Hb will be produced and destroyed in the body on daily basis. Molecular weight of Hb is 67,000 and 3.4 mg of iron present in each gram of Hb. The combination of iron with a porphyrin ring produces the heme. Structure of Heme Heme is derived from porphyrin and porphyrins are cyclic compounds and are formed when 4 pyrrole rings fuse and are linked by methenyl bridges and the four rings are named as I,II,III, IV and Alpha, beta, gamma and delta are the bridges. To the side chain of Porphyrins, four pyrrole rings are attached. We can find one ferrous atom (Fe++) co-ordinated at the centre of the of protoporphyrin IX tetra pyrrole ring. Structure of Globin We can find the tetramer of globin polypeptide chains and each Hb molecule will have 4 Heme units and the subunits of hemoglobin are found to be arranged in a tetrahedral array. And this arrangement will give tight spherical overall appearance (which allows the polar residues being on the exposed surface and keeps the non-polar interactions internal). A molecule of hemoglobin is known to transport up to four oxygen molecules and here iron ion interacts with oxygen molecule to form oxyhemoglobin. Oxyhemoglobin blood is bright red and interactions between the iron–oxygen are very weak and thus can easily be separated without disturbing the heme unit/ the oxygen molecule (completely reversible binding). Deoxyhemoglobin is the hemoglobin molecule without oxygen and dark red.. Primary structure of hemoglobin 141 AA residues will be present in linear sequence of alpha chain contains and non- (, and ) chains will be of 146 amino acids in length (here the beta chain will have valine and histidine as their first residues and Tyr b145 and His b146 found at C-terminal residues). Only 10 residue difference between the delta chain and the beta chain. Secondary structure of hemoglobin We can find nearly 75 percent of the amino acids in or chains in a helical arrangement and 8 helical areas will be found in the chains. Tertiary structure of or chains Sphere type o structure will result during the tertiary folding of each globin chain and this folding brings the Polar or charged side chains directed towards the outer surface of the subunit and non-polar structures directed inwards making Hb water soluble, Heme pocket will be created and is open-toped cleft in the surface and this folding will bring Hb in correct orientation to allow these bonds to form. Quaternary structure of hemoglobin Finally the Hb tetramer will be formed composed of two identical dimers ()1and ()2. These two polypeptide chains are held together tightly (though hydrophobic and ionic interactions andy hydrogen bonding). The two dimers can move with respect to each other. T and R forms of Hb T form (taut structure.

1. Structure of Hemoglobin
Hemoglobin is a chromo protein and is found in red blood cells, it’s a conjugated protein (heme
as prosthetic group + globin as the protein part apoprotein). Adults have 14.0 to 16.0 gm% of Hb
and 90 mg/kg of Hb will be produced and destroyed in the body on daily basis. Molecular weight
of Hb is 67,000 and 3.4 mg of iron present in each gram of Hb.
The combination of iron with a porphyrin ring produces the heme.
Structure of Heme
Heme is derived from porphyrin and porphyrins are cyclic compounds and are formed when 4
pyrrole rings fuse and are linked by methenyl bridges and the four rings are named as I,II,III, IV
and Alpha, beta, gamma and delta are the bridges. To the side chain of Porphyrins, four pyrrole
rings are attached.
We can find one ferrous atom (Fe++) co-ordinated at the centre of the of protoporphyrin IX tetra
pyrrole ring.
Structure of Globin
We can find the tetramer of globin polypeptide chains and each Hb molecule will have 4 Heme
units and the subunits of hemoglobin are found to be arranged in a tetrahedral array. And this
arrangement will give tight spherical overall appearance (which allows the polar residues being
on the exposed surface and keeps the non-polar interactions internal).
A molecule of hemoglobin is known to transport up to four oxygen molecules and here iron ion
interacts with oxygen molecule to form oxyhemoglobin. Oxyhemoglobin blood is bright red and
interactions between the iron–oxygen are very weak and thus can easily be separated without
disturbing the heme unit/ the oxygen molecule (completely reversible binding).
Deoxyhemoglobin is the hemoglobin molecule without oxygen and dark red..
Primary structure of hemoglobin
141 AA residues will be present in linear sequence of alpha chain contains and non- (, and )
chains will be of 146 amino acids in length (here the beta chain will have valine and histidine as
their first residues and Tyr b145 and His b146 found at C-terminal residues). Only 10 residue
difference between the delta chain and the beta chain.
Secondary structure of hemoglobin
We can find nearly 75 percent of the amino acids in or chains in a helical arrangement and 8
helical areas will be found in the chains.
Tertiary structure of or chains
Sphere type o structure will result during the tertiary folding of each globin chain and this
folding brings the Polar or charged side chains directed towards the outer surface of the subunit
and non-polar structures directed inwards making Hb water soluble, Heme pocket will be created

2. and is open-toped cleft in the surface and this folding will bring Hb in correct orientation to
allow these bonds to form.
Quaternary structure of hemoglobin
Finally the Hb tetramer will be formed composed of two identical dimers ()1and ()2. These two
polypeptide chains are held together tightly (though hydrophobic and ionic interactions andy
hydrogen bonding). The two dimers can move with respect to each other.
T and R forms of Hb
T form (taut structure) and R form (the relaxed form).
a) T form
This is the deoxy form of hemoglobin and here the two dimers will interact using ionic bonds
and hydrogen bonds that prevent easy movement of the polypeptide chains and this T form will
have low oxygen affinity form of Hemoglobin.
b) R form
When oxtgen binds to the hemoglobin, some of the ionic bonds and hydrogen bonds between the
dimmers will be ruptured and allow the T state to shift to R or relaxed form, and here the
polypeptide chains will move freely and this form will have high affinity for oxygen.
When O2 binds, it rearranges electrons within Fe+2, making the structure more compact to fit in
the plane of porphyrin and as the Fe is bound to histidine of the globin domain,the entire subunit
undergoes a conformational when Fe moves and this will shift the T state to R state. The 11 and
22 dimers will rearrange and will rotate approximately 15 degrees with respect to each other and
like this oxygen binding to all 4 subunits will be achieved through intersubunit interactions. Due
to co-operative binding of O2 to hemoglobin
Solution
Structure of Hemoglobin
Hemoglobin is a chromo protein and is found in red blood cells, it’s a conjugated protein (heme
as prosthetic group + globin as the protein part apoprotein). Adults have 14.0 to 16.0 gm% of Hb
and 90 mg/kg of Hb will be produced and destroyed in the body on daily basis. Molecular weight
of Hb is 67,000 and 3.4 mg of iron present in each gram of Hb.
The combination of iron with a porphyrin ring produces the heme.
Structure of Heme
Heme is derived from porphyrin and porphyrins are cyclic compounds and are formed when 4
pyrrole rings fuse and are linked by methenyl bridges and the four rings are named as I,II,III, IV
and Alpha, beta, gamma and delta are the bridges. To the side chain of Porphyrins, four pyrrole
rings are attached.

3. We can find one ferrous atom (Fe++) co-ordinated at the centre of the of protoporphyrin IX tetra
pyrrole ring.
Structure of Globin
We can find the tetramer of globin polypeptide chains and each Hb molecule will have 4 Heme
units and the subunits of hemoglobin are found to be arranged in a tetrahedral array. And this
arrangement will give tight spherical overall appearance (which allows the polar residues being
on the exposed surface and keeps the non-polar interactions internal).
A molecule of hemoglobin is known to transport up to four oxygen molecules and here iron ion
interacts with oxygen molecule to form oxyhemoglobin. Oxyhemoglobin blood is bright red and
interactions between the iron–oxygen are very weak and thus can easily be separated without
disturbing the heme unit/ the oxygen molecule (completely reversible binding).
Deoxyhemoglobin is the hemoglobin molecule without oxygen and dark red..
Primary structure of hemoglobin
141 AA residues will be present in linear sequence of alpha chain contains and non- (, and )
chains will be of 146 amino acids in length (here the beta chain will have valine and histidine as
their first residues and Tyr b145 and His b146 found at C-terminal residues). Only 10 residue
difference between the delta chain and the beta chain.
Secondary structure of hemoglobin
We can find nearly 75 percent of the amino acids in or chains in a helical arrangement and 8
helical areas will be found in the chains.
Tertiary structure of or chains
Sphere type o structure will result during the tertiary folding of each globin chain and this
folding brings the Polar or charged side chains directed towards the outer surface of the subunit
and non-polar structures directed inwards making Hb water soluble, Heme pocket will be created
and is open-toped cleft in the surface and this folding will bring Hb in correct orientation to
allow these bonds to form.
Quaternary structure of hemoglobin
Finally the Hb tetramer will be formed composed of two identical dimers ()1and ()2. These two
polypeptide chains are held together tightly (though hydrophobic and ionic interactions andy
hydrogen bonding). The two dimers can move with respect to each other.
T and R forms of Hb
T form (taut structure) and R form (the relaxed form).
a) T form
This is the deoxy form of hemoglobin and here the two dimers will interact using ionic bonds
and hydrogen bonds that prevent easy movement of the polypeptide chains and this T form will
have low oxygen affinity form of Hemoglobin.

4. b) R form
When oxtgen binds to the hemoglobin, some of the ionic bonds and hydrogen bonds between the
dimmers will be ruptured and allow the T state to shift to R or relaxed form, and here the
polypeptide chains will move freely and this form will have high affinity for oxygen.
When O2 binds, it rearranges electrons within Fe+2, making the structure more compact to fit in
the plane of porphyrin and as the Fe is bound to histidine of the globin domain,the entire subunit
undergoes a conformational when Fe moves and this will shift the T state to R state. The 11 and
22 dimers will rearrange and will rotate approximately 15 degrees with respect to each other and
like this oxygen binding to all 4 subunits will be achieved through intersubunit interactions. Due
to co-operative binding of O2 to hemoglobin