This document compares and contrasts the proteins hemoglobin and myoglobin. It discusses their structures, functions, and key differences. Hemoglobin is an oxygen transport protein found in blood consisting of four subunits, while myoglobin is an oxygen storage protein located in muscle tissue. Both contain a heme group that binds oxygen, but hemoglobin can bind four oxygen molecules total due to having four subunits, each with their own heme group. Myoglobin only has one subunit and heme group and thus can only bind one oxygen molecule. The document also covers cooperativity in hemoglobin and how oxygen binding causes a conformational change in its structure.

1. hemoglobin And
Myoglobin
Presented By: Abdul Basit (42512)
Usama Aamir (41585)
Presented To: Dr. Asma Abro

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Contents
Introduction
Structure Of hemoglobin And Myoglobin
Functions Of hemoglobin And Myoglobin
Comparison Between hemoglobin And Myoglobin
Cooperativity and Allosteric Regulation in hemoglobin
Conclusions
References

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Introduction
Because of its red colour, the red blood pigment has been of interest since antiquity.
First protein to be crystallized - 1849.
First protein to have its mass accurately measured.
First protein to be studied by ultracentrifugation.
First protein to associated with a physiological condition.
First protein to show that a point mutation can cause
problems.
First proteins to have X-ray structures determined.
Theories of cooperativity and control explain hemoglobin
function

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Pathway
Lungs hemoglobin Myoglobin
O2
O2
Tissue

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hemoglobin
 heme(Blood)-Globin(Protein)
 heme is a prosthetic group
 Only Fe++ Binds Oxygen
 α2 β2 Heterotetramer
 Transport Protein
Myoglobin
 Myo(Muscle)-Globin(Protein)
 Storage Protein
 Monomer (Single Polypeptide Chain)

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Structure of hemoglobin And Myoglobin
heme
N α Chain
Chain β N
N β Chain
N α Chain

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Functions of hemoglobin And Myoglobin
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

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11. Comparison
Myoglobin
 Myoglobin is a globular protein.
Water soluble.
Ligand is oxygen.
Myoglobin exist in muscle(tissue).
Myoglobin is a storage protein.
hemoglobin
hemoglobin is also a globular protein.
Water soluble.
Ligand is oxygen.
hemoglobin exist in blood.
Hemoglobin is a transport protein.
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Myoglobin hemoglobin
 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)
 Take O2 From lungs to the tissues
(Including Muscles)
 Oligomeric nature ( More than one
polypeptide chain)
 Actually made up of 2 α and 2 β side
chains
 Quartnery structure
 Also Attaches with histidine residues
to impart some kind of buffering
properties to blood

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Myoglobin hemoglobin
 Higher affinity towards oxygen
because myoglobin needs to grab
the oxygen from hemoglobin.
 Can bind to one heme group
(prosthetic group).
 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.

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Cooperativity
 A simple 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 will affect on the affinity
of other subunits.

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Conclusion
 Animals Have Widely Varying 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’s Iron 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
 Sickle Cell Anaemia (SCA) is a Genetic Disease of hemoglobin.

17. References
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Oxygen binding by myoglobin & hemoglobin. (2004, October 1). Retrieved
from https://www.bio.cmu.edu/courses/03231/LecF04/Lec13/le
c13.html
Bucci, E., Razynska, A., Kwansa, H., Gryczynski, Z., Colli ns, J. H., &
Fronticelli, C. (1996). Positive and negative cooperativities at subsequent
steps of oxygenation regulate the allosteric behavior of multistate
sebacylhemoglobin. Biochemistry, 35, 3418 - 3425

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