Structure and function of hemoglobin and myoglobin

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
includes :
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
17
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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