Globular proteins like hemoglobin and myoglobin have complex tertiary and sometimes quaternary structures that allow them to perform important biological functions. Hemoglobin is a transport protein that carries oxygen in the bloodstream through a heme group and heterotetrameric structure. Myoglobin is a storage protein found in muscle tissue that stores oxygen through a monomeric structure. Both proteins bind oxygen through histidine residues interacting with iron in their heme groups, but hemoglobin has higher cooperativity and can bind four oxygen molecules at once. Proteins are essential for many biological processes like structure, movement, transport, immune response and more.

1. Conformation and function of Globular
Protein with special reference to
Structure and function of Hemoglobin
and Myoglobin. Biological significance
of Protein
Presented By: Bushra Ashraf(7009)
Presented To: Dr. Asim Raza Basra
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2. Contents
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Introduction of Globular protein
Structure and function of Globular Protein
Functions Of hemoglobin And Myoglobin
Comparison Between hemoglobin And
Myoglobin
 Cooperativity and Allosteric Regulation in
hemoglobin
Significance of protein
References

3. Introduction of Globular Protein
 Globular Protein • Have complex tertiary and sometimes
quaternary structures.
 Folded into spherical (globular) shapes. • Usually
soluble as hydrophobic side chains in center of
structure.
 Roles in metabolic reactions. • E.g. enzymes,
haemoglobin in blood. Bio-Resource
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4. Pathway
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Lungs
O2
O2
Myoglobin
Tissue
Hemoglobin

5. Hemoglobin
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 heme(Blood)-Globin(Protein)
 heme is a prosthetic group
 Only Fe++ BindsOxygen
 α2 β2 Heterotetramer
 Transport Protein
Myoglobin
 Mo(Muscle)-Globin(Protein)
 Storage Protein
 Monomer (Single Polypeptide
Chainy)

6. Structure of hemoglobin And Myoglobin
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heme
N αChain
Chain β N
N βChain
N αChain

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9. Functions of hemoglobin And Myoglobin
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During this process, the hemoglobin
macromolecule undergoes conformational
changes due to the binding and unbinding of
oxygen and carbon dioxide.And it include :
Oxygen Pickup
Oxygen Delivery
Carbon Dioxide Pickup
Carbon Dioxide Delivery

10. Comparison
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Myoglobin is a storage protein. Hemoglobin is a transport protein.
Myoglobin
 Myoglobin is a globular protein.
Water soluble.
Ligand is oxygen.
Myoglobin exist in muscle(tissue).
Hemoglobin
hemoglobin is also a globular protein.
Water soluble.
Ligand is oxygen.
hemoglobin exist in blood.

11. Myoglobin
Bind And Release O2 to muscle
cell.
 Monomer (Single polypeptide
Chain)
 8 Helices segments
 Tertiary Structure
Histidine is present helps to
attach with Fe (Iron)
(Including Muscles)
 Oligomeric nature ( More than one
polypeptide chain)
Actually made up of 2 α and 2 β side
chains
 Quartnery structure
AlsoAttaches with histidine residues
to impart some kind of buffering
11properties to blood
 Take O2
Hemoglobin
From lungs to the tissues

12. Myoglobin
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Higher affinity towards oxygen
because myoglobin needs to grab
the oxygen from hemoglobin.
 Can bind to one heme group
(prosthetic group).
Hemoglobin
Comparatively lower
affinity towards oxygen
 hemoglobin have two states
 R state (Oxyhemoglobin)And T
state (Deoxyhemoglobin)
Can Bind to 4O2 Molecules each
subunit has a heme group.

13. Cooperativity
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Asimple phenomenon in which when one oxygen is bind to one
subunit the affinity for O2 at the other subunit increases.
Allosteric regulation
Simply,binding of one ligand to a subunit willaffect on the affinity
of othersubunits.

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15. Conclusion
15SickleCellAnaemia (SCA) is a Genetic Disease of hemoglobin.
 Animals Have WidelyVarying O2 Need
 hemoglobin and Myoglobin are Related, but Have Different Functions
 hemoglobin has Four Subunits and heme group.
 Myoglobin has One of Each Bind of O2 by heme’sIron Pulls up on a Histidine and
Change’s hemoglobin Shape Changing hemoglobin Shape Converts hemoglobin from
T-state to R-state
 R-state Binds Oxygen Better.
 T-state Releases O2 Better

16. Biological Significance of Protein
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 Protein has a critical physiological
function. Protein is primarily used in
the body to build, maintain, and repair
body tissues.
 In the event that protein intake is
greater than that required by the body
for this primary function, excessive
protein is converted to energy for
immediate use or stored in the body as
fat.
 Protein energy will be used only after
other energy sources (carbohydrate
and fat) are exhausted or unavailable.

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 Proteins transport small molecules
through the organism. Hemoglobin is
the protein that transports oxygen to
the cells and it is called as transport
protein.
 Proteins called antibodies help rid
the body of foreign protein and help
prevent infections, illnesses and
diseases.
 protein help store other substance in
the organism. For example, iron is
stored in the liver in a complex with
the protein ferritin.

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 Proteins help mediate cell
responses, such as the protein
rhodopsin, found in the eye and
involved in the vision process.
 Proteins make up a large protein of
muscle fiber and help in the
movement of various parts of our
bodies.
 Skin and bone contain collagen, a
fibrous protein

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