Difference between hemoglobin and myoglobin
The main difference between hemoglobin and myoglobin is that hemoglobin is a globin protein that transfers oxygen to all parts of the body in the organism, while myoglobin is a globin protein that transfers oxygen only to muscle cells.
Hemoglobin vs. myoglobin
Breathing is a fundamental process of life. Almost all organisms require the transport of oxygen to all cells in your body for their survival. Hemoglobin and myoglobin are two basic globin proteins in living organisms that bind to oxygen and transfer it to cells. But there are several differences between them. Hemoglobin transfers oxygen from the lungs to all parts or cells of the body in vertebrates, as well as some invertebrates, while myoglobin transfers oxygen to muscle cells only. Hemoglobin is made up of 4 polypeptide chains, while myoglobin is made up of a single polypeptide chain. Hemoglobin is found in the bloodstream, while myoglobin is found in muscle cells.
Comparative chart
| Hemoglobin | Myoglobin |
| Hemoglobin is a globin protein that transfers oxygen from the lungs to all parts of the body. | Myoglobin is a globin protein that transfers oxygen to muscle cells. |
| Structure | |
| It has a tetrameric structure. | It has a monomer structure. |
| Chain | |
| It is made up of 4 chains of two different types, that is, alpha and beta, delta, gamma or epsilon (based on the type of different types of hemoglobin). | It is composed of a single polypeptide chain. |
| Location | |
| It is found throughout the body. | It is found in muscle cells. |
| Ability to link | |
| Has the ability to bond with CO2, NO, CO, O2, and H + | It has the ability to join the O2. |
| Number of hemes | |
| It has four hemes, one in each of the subunits. | There is a heme in the myoglobin |
| Number of oxygen molecules | |
| Four oxygen molecules can bind to hemoglobin | A single oxygen molecule binds to myoglobin |
| Molecular weight | |
| Its molecular weight is 64 kDa. | Its molecular weight is 16.7 kDa. |
| Affinity for bonding with oxygen | |
| It has a low affinity to bind oxygen. | Myoglobin has a high affinity for binding to oxygen. |
| Blood concentration | |
| It has a high concentration of red blood cells. | It has a low concentration in the blood. |
| Curve | |
| Shows the sigmoid junction curve. | Show the hyperbolic curve |
| Also know as | |
| Also known as Hb | Also known as Mb |
| Function | |
| Hemoglobin binds to oxygen and is transported to all parts of the body through the blood. | Myoglobin transfers oxygen only to muscle cells, which provides help at the time of oxygen starvation. |
Hemoglobin is a multi-subunit globin protein with a quaternary structure and is made up of four polypeptide chains, two α subunits, and two β subunits. Each alpha chain is made up of 144 residues and each beta chain is made up of 146 residues. Opposite subunits like alpha and beta associate more strongly than similar alpha-alpha or beta-beta subunits. It is a metalloprotein that contains iron. In hemoglobin, each of the four subunits is attached to a non-protein prosthetic heme group, where the oxygen molecule is attached. So, it means that hemoglobin can bind four oxygen molecules with four heme groups from each chain. It has low affinity for oxygen in its deoxygenated state, but when the first oxygen molecule binds to hemoglobin, causes a change in its structure that facilitates the binding of other oxygen molecules. This process is called allosteric (through space) interaction / cooperativity. Hemoglobin is in excess in red blood cells and gives them a red color. It involves the transport of oxygen and carbon dioxide to or from all parts of the body. It also involves the metabolism of erythrocytes and also maintains the pH of the blood.
Types
- Hemoglobin A1 (Hb-A1).
- Hemoglobin A2 (Hb-A2).
- Hemoglobin A3 (Hb-A3).
- Embryonic hemoglobin.
- Glycosylated hemoglobin.
- Fetal hemoglobin (Hb-A1).
What is myoglobin?
Myoglobin is a monomeric globin protein that has a secondary structure. It is composed of a single polynucleotide chain that is composed of 153 residues. It has a single heam group attached to its single polypeptide chain. So a single oxygen molecule can bind to it. But its binding capacity is higher than that of hemoglobin, so it acts as an oxygen-storing protein that is released during muscle function. It is found in muscle cells and provides them with oxygen when they need it. It helps the body in conditions of oxygen shortage, especially in anaerobic conditions. It also regulates body temperature. Myoglobin has no type.
Key differences
- Hemoglobin is a globin protein that transfers oxygen from the lungs to all parts of the body, while myoglobin is a globin protein that transfers oxygen only to muscle cells.
- Hemoglobin has a tetramer structure, while myoglobin has a monomer structure.
- Hemoglobin is made up of 4 polypeptide chains, while myoglobin is made up of a single polypeptide chain.
- Hemoglobin is present in red blood cells, while myoglobin is found in muscle.
- Hemoglobin has four heme groups, so it can bind to four oxygen molecules, but myoglobin has only one heme group, so it can bind to a single oxygen molecule because the heme group is the binding site for oxygen.
- Hemoglobin can bind with O2, CO2, CO, NO, BPH, and H +, while myoglobin can bind only with O2.
- Hemoglobin has a molecular weight of 64 kDa, while myoglobin has a molecular weight of 16.7 kDa.
- Hemoglobin has a low affinity to bind oxygen, while myoglobin has a high affinity to bind oxygen.
- Hemoglobin involves the transport of oxygen and carbon dioxide to or from all parts of the body, in the metabolism of erythrocytes and also maintains the pH of the blood while myoglobin is found in muscle cells and provides them with oxygen as require and also regulates body temperature.
Final Thought
From the above discussion, it is concluded that hemoglobin is a tetramer made up of four polynucleotide chains and carries oxygen and carbon dioxide to all parts of the body, while myoglobin is a monomer made up of a single nucleotide chain and carries oxygen. to muscle cells only on the requirement.