Protein Function
Monique Stage
Competency 208.5.3
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Protein Function
Myoglobin and Hemoglobin
Myoglobin is a protein function that is found in the blood and has a similar
molecular structure to hemoglobin.
Both hemoglobin and myoglobin serve to bind and deliver oxygen to the various
parts of the body for the respective activities that the body undertakes.
The basic functions of this globin's is to improve the concentration of molecular
oxygen dissolved in the biological fluids of all vertebrates and some
invertebrates.
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Myoglobin and Hemoglobin
 The obvious importance of both hemoglobin
and myoglobin in the vertebrate life Cannot
be overemphasized because it is obvious
 The reason for studying both of this globin
is basically due to their excellent and well
characterized models that basically illustrate
the principle of protein function, dynamics
and structure.
 In this context, the basic aspects of these two that will be explored will be
concerned with oxygen binding and allostery.
Myoglobin Structure
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 The Myoglobin is a monomeric protein and is made up of 153 amino acid
residues.
 The basic components that it is made up of include eight @-helices and this
are connected through turns with the oxygen binding site.
 The myoglobin has a globular structure too and contains a prosthetic or a
heme group
 The heme group is basically necessary for the main function of the
myoglobin which is to carry oxygen to the various parts of the vertebrates
muscles.
 The two various forms of existence in which myoglobin exists are essentially
the oxygen bound form which is also referred to as oxymyoglobin or the
oxygen free state which is also referred to as the deoxymyoglobin.
Myoglobin Structure Cont.:
 The existence of myoglobin is in the sense that it is a protein that exists and
binds oxygen with its heme group for instance the hemoglobin.
 At the heme, there is a iron atom located at the center and protoporphyrin
organic component.
 The heme group is responsible for the red pigment color that is found in
blood (Davidson, & Sittman, 1999).
 The organic component that is mentioned in this context is linked together
by methane bridges. The oxidation of the iron atom is responsible for the
color of blood at the muscle.
 Further, at the center of the protoporphyrin the iron atom is bonded to
nitrogen atoms and this forms four pyrrole rings.
Myoglobin Structure Cont.
 The iron atom is always open at the end of each
heme group and can form two additional bonds
at the end or each heme group
 The bonding sites that these create are what
is essentially referred to as coordination sites.
 These coordination sites are recurrent and
go to the fourth and fifth and sixth residual bonds.
The sixth residual bond and rather the coordination site is occupied by the
protein and available for oxymyoglobin.
Oxygenated and Deoxygenated
states of Hemoglobin
 The basic difference between the oxygenated and deoxygenated states of
hemoglobin can be effectively traced to their structural components.
 At the state of deoxyhemoglobin, the subunits of hemoglobin are held together
by eight salt bonds that (Tropp, 2012) come between the polypeptide and
hydrogen bonds and this ensures noncovalent interactions.
 When oxygenation occurs, the salt bonds breaks and a new set of hydrogen
bonds form.
 In essence, the subunit bonds are weaker in oxyhemoglobin than in
deoxyhemoglobin.
 The conformation of the deoxyhemoglobin is therefore called the Tense
conformation whereas that of oxyhemoglobin is called relaxed conformation
based on the nature of interactions.
Sickle Cell Anemia
 The sickle cell anemia is believed to be one of
the most common forms of inherited anemia.
 The characteristics of this disease is
that the body makes sickle-shaped red
blood cells.
The red blood cells in this case take
the shape
of a crescent and hence the name sickle-cell.
Sickle Cell actual presentation
Diseased Cells vs. Normal Cells
 There is one main distinction in the delivery of oxygen between diseased
cells and normal cells.
 One thing that really stands out is the fact that diseased cells tend to
cluster up together and this makes it harder for them to traverse along the
various body muscles and to ensure the effective transportation of oxygen
to the various body parts as required at the specific time.
 A normal cell is smooth, disk-shaped and flexible and this makes it easy for
this cells to move through (Jones, 2008) the body tissues and deliver oxygen
to the respective body tissues. Sickle cells have a crescent shape that they
obtain once they loose their oxygen, are sticky and stiff and this makes it
hard for them to move freely and deliver the oxygen requirements.
Molecular Inheritance of Sickle Cell
Molecular Inheritance of Sickle Cell
Cont.
 Sickle cell disease is high associated with inheritance and is believed to
result from the contributions and rather aspects of mutation (Bloom, 1995).
 The structures in our bodies that contain genes are called chromosomes
and for a normal person there are 23 pairs of chromosomes and rather 46
of them.
 The 11th pair of chromosomes contains the responsible gene for
hemoglobin production (Jones, 2008).
 An error in the gene or rather what is called mutation is what results to a
sickle condition.
 The belief is that this originated from some part of the world where malaria
is more prevalent since as it is observed, people with sickle cell tend to be
tolerant to malaria and this is better explained in the diagram above.
References
 Jones, P. (2008). Sickle cell disease. New York, NY: Chelsea House Publishers.
 Bloom, M. (1995). Understanding Sickle Cell Disease. Jackson: University
Press of Mississippi.
 Tropp, B. E. (2012). Molecular biology: Genes to proteins. Sudbury, Mass:
Jones & Bartlett Learning.
 Davidson, V. L., & Sittman, D. B. (1999). Biochemistry. Baltimore, Md:
Lippincott, William & Wilkins.