Human body works in a coordinated way. Every single molecule is performing its own function and never disturbing the other. However, if any of the molecule is disturbed, it can result in pathological conditions.

Discussed below are two of the most important molecules that are quite necessary for human survival. Both of these molecules have a lot in common but here we will be discussing their differences,

What is Hemoglobin?

Iron plays an essential role in blood production. About 70 percent of human body’s iron is present in the red blood cells of their blood called hemoglobin. Hemoglobin is the iron-containing metalloprotein responsible for oxygen transport and is present among RBCs in all vertebrates and tissues of some of the invertebrates. Hemoglobin in blood helps in transport. It is responsible for oxygen transport from the lungs to the other parts of the body. Hemoglobin acts as a two-way respiratory carrier that is responsible for transport of oxygen from the lungs to the tissues and also the return transport of carbon dioxide. Besides transport, hemoglobin also plays a role in erythrocytes metabolism that eventually results in maintenance of blood pH.

What is Myoglobin?

An iron and oxygen binding protein are present in skeletal muscle tissues that is commonly called as myoglobin. It is present in all mammals and some of the vertebrates. Myoglobin has a distant connection with hemoglobin in a way that hemoglobin is present in RBCs while myoglobin is present in muscles. Myoglobin showcases higher affinity for oxygen. It does not allow cooperative binding with oxygen. Another important function of myoglobin is its role in the detoxification of reactive oxygen species. Myoglobin transports oxygen to muscle cells known as myocytes. The red color of muscles is due to myoglobin in vertebrates. Myoglobin stores energy and uses that energy in conditions like starving or anaerobic respiration. Myoglobin has a vital role in regulation of body temperature.

Difference between Myoglobin and Hemoglobin

 HemoglobinMyoglobin
Hemoglobin showcases a tetramer structureMyoglobin has a monomer structure
Hemoglobin is composed of four polypeptide chains named as two alpha chains and two beta chains.Myoglobin is formed of a single polypeptide chain.
Hemoglobin is formed of 4 globin and 4 heme chains.Myoglobin is composed of one heme and one globin chain.
Hemoglobin can bind with oxygen, carbon dioxide, CO, NO, BPH and H+Myoglobin can bind only with oxygen.
Hemoglobin is present all over the blood in bodyMyoglobin is present in muscles only
Hemoglobin named as Hb often, is present in RBCsMyoglobin, Mb is present in skeletal muscle tissues.
Hemoglobin transports oxygen throughout the bodyMyoglobin transports oxygen to muscles carrying it from blood.
Hemoglobin shows high oxygen binding affinityMyoglobin has low oxygen carrying affinity than hemoglobin.
Hemoglobin forms a sigmoid binding curveMyoglobin shows a hyperbolic curve.
Hemoglobin functions as a transport proteinMyoglobin is a type of storage protein.
4 types of hemoglobin exist in human bodyMyoglobin exist as a single type in human body.
Hemoglobin can bind with 4 oxygen moleculesMyoglobin can bind with a single oxygen atom
Hemoglobin exhibits Bohr effectMyoglobin does not show Bohr effect
 The molecular weight of hemoglobin is 64kDaThe molecular weight of myoglobin is only 16.7kDa
Hemoglobin is affected by the surrounding temperature conditionspH does not really affect Myoglobin

Hemoglobin and Myoglobin, both hemeproteins have so much in common. How two of them bind with the most significant molecule of body, oxygen, makes a difference in both of them. Although both Hemoglobin and Myoglobin have iron as their central atom but Myoglobin being monomeric and Hemoglobin being tetrameric hemoprotein is what defines the structural difference between both of these molecules.

Hemoglobin is present in RBCs and RBCs are present in blood so technically hemoglobin is present in all the human body while myoglobin is present only in muscle cells. Hemoglobin is all protein and is known for its oxygen-carrying pigment.

Due to its role in transport, hemoglobin plays a vital role in the maintenance of the body by transporting oxygen and carbon dioxide throughout the human body. On the other hand, myoglobin only works for muscles, it receives oxygen from RBCs and transports it to the muscle cells. The muscle cells then use this oxygen for processes like cellular respiration to generate ATP.

Sana Riaz
Author

Sana has just completed her MPhil in Microbiology. She loves reading books and the latest discoveries in sciences.

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