Protein
is the main component in living cells that play an important role in
the life process. Protein plays a role in the structure and function of
all living cells and viruses. protein allies in the form of enzymes as
catalysts in a variety of biochemical processes. As a means of
transport, ie hemoglobin protein binds and transports oxygen in the form
of (Hb-O) to all parts of the body.
Protein
also serves as a protector, as the antibodies if your body is possessed
by foreign substances, as well as the control system in the form of
hormones,
Protein is a very important
component of protoplasm addition to the water. The role of proteins in
cells, among others: 1. As a catalyst for many chemical reactions
contained in the cell, namely as components in the enzyme. 2. Giving
cell structural strength, namely tubulin, actin and myosin are involved
in the formation of sitoskelet. 3. Monitoring the permeability of the
membrane, the proteins that make up the cell membrane 4. Cause movement
that occurs in sel5. Monitor the activities of the cell 6. Set the
required levels of metabolites One of the functions of proteins are
proteins as a means of transportation.
Transport
Proteins: Hemoglobin and heme MioglobinProtein found in hemoglobin and
myoglobin function in binding oxygen, oxygen transport and
photosynthesis.
Figure 3. Oxygen binding curve of hemoglobin and myoglobin
Hemoglobin also transports H and CO2
In
addition to carrying oxygen from the lungs to the tissues, hemoglobin
also carries H and CO2 from the tissues to the lungs and kidneys for
excreted. In the cell, organic fuel is oxidized by mitochondria to form
CO2, water and other substances. Formation of CO2 increase in the tissue
levels of H because hydration of CO2 produces H2CO3, a weak acid that
dissociates to form H and HCO3-.
Hemoglobin
Hemoglobin
is metaloprotein (iron-containing protein) in red blood cells that
serves as a carrier of oxygen from the lungs throughout the body in
mammals and other animals. Hemoglobin is also the bearer of carbon
dioxide back to the lungs to the body exhaled. Hemoglobin molecule
consists of globin, Apoprotein, and four heme groups, an organic
molecule with an iron atom. Mutations in these genes lead to a class of
proteins hemoglobin decreased disease called hemoglobinopathy, among
which the most common is sickle cell anemia and thalassemia. The
structure of the central heterocyclic ring molecules are known to hold
one atom porphyrin iron, the iron atom is a site / shop oxygen bond.
Porphyrin-containing iron called heme. Hemoglobin name is a combination
of heme and globin; globin as a generic term for globular proteins.
There are several proteins containing heme and hemoglobin is the best
known and most widely studied.
Cluster heme
In adult humans, hemoglobin
tetramer form (containing 4 subunit proteins), consisting of each of the
two alpha and beta subunits bound nonkovalen. Subunit-subunitnya
structurally similar and similarly sized. Each subunit has a molecular
weight of approximately 16.000 Dalton, so the total molecular weight
tetramernya to about 64.000 Dalton. Each subunit contains a heme
hemoglobin, so the overall hemoglobin has a capacity of four oxygen
molecules: In the center there is a heterocyclic ring molecule known as
porphyrin hold one atom of iron, the iron atom is a site / shop oxygen
bond. Porphyrin called heme iron-containing hemoglobin Each subunit
contains a heme, so overall hemoglobin has a capacity of four oxygen
molecules. In the iron heme molecule is attached and delivers oxygen and
carbon dioxide through the blood, these substances also makes our blood
red.
Reaction stages:
- Hb + O2 <-> HbO2
- HbO2 + O2 <-> Hb(O2)2
- Hb(O2)2 + O2 <-> Hb(O2)3
- Hb(O2)3 + O2 <-> Hb(O2)4
·
Hb + 4O2
-> Hb(O2)4
Currently,
measurement of hemoglobin levels in the blood have been using automatic
machines. In addition to measuring hemoglobin, this machine can also
measure some other blood components. Measurement machine will break down
hemoglobin into a solution. Hemoglobin in solution is then separated
from other substances by using a chemical called cyanide. Furthermore,
the specific irradiation, hemoglobin levels were measured based on the
value of successful light absorbed by hemoglobin What does it mean when
the low hemoglobin levels? Hemoglobin concentration in the blood is low
known as anemia. There are many causes of anemia among the most frequent
are bleeding, malnutrition, bone marrow disorders, chemotherapy and
congenital abnormalities of hemoglobin. What does it mean when a high
hemoglobin levels high hemoglobin levels can be found in people who live
in the highlands and smokers. Some diseases such as pneumonia, tumors
and bone marrow disorders can also increase the levels of hemoglobin.
Myoglobin
Myoglobin (BM 16 700, abbreviated
Mb) is an oxygen-binding protein that is relatively simple, it is found
in large concentrations in bone and heart muscle, making it red tissue
that serves as a store of oxygen and as a carrier of oxygen increases
the rate of oxygen transport in muscle cells. Diving mammals such as
whales dive for a long time, has a high concentration of myoglobin in
the muscles. Proteins such as myoglobin are also commonly found in
single-cell organisms. Myoglobin is a single polypeptide with 153 amino
acid residues and the heme molecule. Component of myoglobin protein
called globin, a single polypeptide chain containing eight α-helices
(Fig. 1). Approximately 78% of the amino acid residues of the proteins
found in the α-helix is.
Globin chain folds to form a gap
that almost filled the heme group. Free heme [Fe 2] has a high affinity
for O2 and unidirectional oxidized form hematin [Fe3]. Hematin can not
bind O2. Nonkovalen interactions between amino acid side chain and the
porphyrin ring containing nonpolar side slit tissue oxygen increases
heme affinity for O2. Increased affinity Fe2 protect from oxidation and
allows the reversible oxygen binding. All the amino acids that interact
with nonpolar except two histidine heme, which binds directly to the
heme iron atom and the other histidine stabilizes the tissue of oxygen.
When the oxygen bound to the heme-free, position the axis of molecular
oxygen on Fe-O bond angle (Fig. 2a), in contrast to this, when CO2 binds
to free heme Fe, C and O are on a straight line (Fig. 2b). Both cases
reflect the geometry of the orbital hybridization of each ligand. In
myoglobin, His64 (His E7), at the O2 bind heme, too far away to
coordinate with the heme iron, but interacting with a ligand bound to
the heme. These residues are called distal his, which did not affect the
binding of oxygen (Fig. 2c) but may block the binding of linear CO,
explaining the reduction of CO binding to heme.
Oxygen fixation
protein is a
constituent of the blood that is myoglobin oxygen binding. Myoglobin
unsuitable as an oxygen-carrying protein, but it is effective as an
oxygen storage protein. Myoglobin in red muscle tissue that binds oxygen
in a state of lack of oxygen to be released so that it can be used by
the mitochondria of muscle for oxygen-dependent ATP synthesis.
Oxygenated myoglobin, the oxygen molekulo sixth coordination position of
the iron atom and the movement of His F8 and residue that covalently
binds to the His F8 ring plane. This movement raises a new conformation
for the parts of the protein.
When O2 binds to myoglobin, the
bond between an oxygen molecule with Fe2 is perpendicular to the plane
of the heme. The second O2 molecule binds to 121o angle to the plane of
the heme and directed away from the distal histidine. Pengikiatan oxygen
bond breaking accompanied by anatar salt residue on a whole subunit
carboxyl terminal. Binding of O2 further simplified because the number
of bonds broken salt becomes less. These changes affect the structure of
hemoglobin. One pair of sub-units α / α hold the rotation of the
partner / other, so menempatlkan tentramer and enhance heme affinity for
O2. When oxygenation, deoksihemoglobin iron atom moves into the heme
ring plane. This movement is transmitted to the proximal histidine,
which is moving toward the field and in the ring and the amino acid
residue attached to his F8. The oxygen has been released from hemoglobin
into the tissues, hemoglobin then mengamgkut CO2 and protons into the
lungs. Excessive myoglobin can cause damage to the kidneys and
eventually cause kidney failure.
Seruloplasmin
Seruloplasmin is an enzyme with copper substance that serves as a catalyst in organic reactions
4 Fe2+
+ 4 H+ + O2 <=> 4 Fe3+ + 2 H2O
Ceruloplasmin activity of the enzyme has ferrioxidase that
converts ferrous iron in the form of the cells and in the form of store with
transferrin and ultimately used by the bone marrow to the manufacturing process
of erythrocytes. Ceruloplasmin is the main form of copper minerals are present
in the circulation of the blood (plasma). Forms of Cu in the body bind to a
protein complex that is 90% bound to globulin in the form of ceruloplasmin and
10% by albumin. Ceruloplasmin have activity as an enzyme capable of converting
ferroksidase iron in the ferrous form of the cells and in the form of store
with transferring and ultimately used by the bone marrow to the process of
making erythrocytes (erytropoiesis). Ceruloplasmin is α-2-globulin. This
protein is blue because it contains copper and carry 90% of copper present in
the plasma. Myoglobin myoglobin is a protein that is a constituent of the blood
that binds oxygen. Myoglobin unsuitable as an oxygen-carrying protein, but it
is effective as an oxygen storage protein. Myoglobin in red muscle tissue that
binds oxygen in a state of lack of oxygen to be released so that it can be used
by the muscle mitochondria for ATP synthesis are dependent on oxygen.
