Haemoglobin (or hemoglobin) and myoglobin are heme proteins that act as oxygen binding proteins. The main point of difference between the two lies in the fact that haemoglobin is found all over the body and myoglobin is found only in muscle tissues.
Let us take an overview of Hemoglobin and Myoglobin before moving on to their differences.
Table of Contents
What is Haemoglobin?
Haemoglobin is a globular protein found in the RBCs, which are responsible for the transport of oxygen from the lungs to the entire body. It is a tetrameric protein made up of two alpha and two beta subunits. Each of the four chains is associated with an iron or heme group which binds with one oxygen molecule each.
What is Myoglobin?
Myoglobin is a globular protein found in the muscles which are responsible for the storage of oxygen in the muscle cells. This stored oxygen is later used up by us while doing different activities. It is a monomeric protein made of a single type of subunit. It has a higher binding affinity than haemoglobin towards oxygen because myoglobin tends to keep oxygen in an oxidation state of +3, which stabilizes it.
Haemoglobin vs Myoglobin
|
Haemoglobin |
Myoglobin |
| Function | |
| It carries oxygen from the lungs to the rest of the body. | It stores oxygen in the muscle cells, which can be utilised as energy. |
| Structure | |
| Heterotetramer | Monomer |
| Quaternary structure | Tertiary structure |
| Made up of four polypeptide chains – two alpha and two beta chains | Made up of a single polypeptide chain |
| Protein Type | |
| It is a storage protein | It is a transport protein |
| Type of Curve | |
| It shows a sigmoid curve in a graph of oxygen dissociation. | It shows a hyperbolic curve in a graph of oxygen dissociation. |
| Affinity towards oxygen | |
| Comparatively lower affinity to oxygen can bind to CO2, CO and NO as well | Higher affinity towards oxygen |
| Molecular weight | |
| 64kDa | 16.7kDa |
| Location | |
| Present all over the body | Present only in heart and muscle cells |
| Abbreviation | |
| Hb | Mb |
| Concentration in Blood | |
| Higher concentration in blood | Higher concentration in muscles |
Keep exploring BYJU’S Biology to learn more about haemoglobin and myoglobin.
Frequently Asked Questions
What are the similarities and differences between myoglobin and haemoglobin?
- Both are globular proteins
- Ligand for both myoglobin and haemoglobin is oxygen
- Both haemoglobin and myoglobin give red colour to muscles and blood.
What are the structural differences between myoglobin and haemoglobin?
Haemoglobin has a quaternary structure composed of two alpha and two beta subunits, whereas myoglobin has a tertiary structure.
What are the functions of haemoglobin and myoglobin?
Haemoglobin functions as an oxygen carrier from the lungs to the entire body, and myoglobin functions as a storer of oxygen in the muscle cells.
SN4 preparation and properties and structure