Chemical nutrients which are essential for building tissues in the body are called proteins. They are also responsible for the repair of worn out cells. There are mainly three types of proteins in the human body that are globular proteins, membrane proteins and fibrous proteins.
Globular Protein vs Fibrous Protein
The main difference between globular proteins and fibrous proteins is that globular proteins are mainly used to form cellular messengers, amino acids, enzymes whereas fibrous proteins are mainly used in the formation of tendons, connective tissues, and fibers.
Also, the structure of both these proteins is very different from each other. The shape of a globular protein is a sphere while the shape of a fibrous protein is like an elongated strand. The globular protein also has a property that enables it to form colloids with water and thus, it gets dissolved in it.
On the other hand, fibrous proteins are not at all soluble in water, weak bases, or weak acids. They are only soluble strong acids. In general, the fibrous protein is present in the form of wires and rods. An example of globular protein is hemoglobin while examples of fibrous protein are collagen, elastin, and keratin.
Comparison Table Between Globular Proteins and Fibrous Proteins
| Parameters of Comparison | Globular Proteins | Fibrous Proteins |
| Definition | Globular protein is a type of protein that is soluble and tends to be involved in metabolic functions. | Fibrous proteins are a type of proteins that are insoluble and that build up the main structural elements of the body. |
| Shape and structure | Globular proteins are round or spherical in shape and have a folded ball like structure. | Fibrous proteins are long and narrow in shape and have a helical or sheet like structure. |
| Solubility in different solvents | Globular proteins are soluble in water, acids and bases. | Fibrous proteins are only soluble in strong acids. They are insoluble in water, and any other weak acids and bases. |
| Intermolecular forces | Globular proteins have a weak intermolecular interaction between them. | Fibrous proteins have a strong intermolecular interaction between them. |
| Function | Globular proteins are mainly responsible for the formation of cellular messengers, amino acids and enzymes. | Fibrous proteins are mainly responsible for the formation of tough tissues. They are used in the formation of tendons, connective tissues and fibers. |
What is Globular Protein?
Globular proteins are spherical proteins and are water soluble. Globular proteins are responsible for the formation of many essential structures in the human body. They can form enzymes which are useful in catalyzing organic reactions that take place in organisms.
They form messengers that helps in the transmission of messages throughout the body in order to regulate biological processes. They also transport other molecules through membranes. They perform all the regulatory roles in the body. The globular proteins are held together by weak intermolecular hydrogen bonding.
They are made up of primary, secondary, tertiary, and sometimes also quaternary structures. They consist of straight-chain structure of secondary structures that can join polypeptide chains and can also change directions. Examples of globular proteins are enzymes, hormones, hemoglobin, immunoglobulin, etc.
What is Fibrous Protein?
Fibrous proteins are also known as scleroproteins. They are in the shape of elongated strands like rods and wires, of polypeptide chain which results in the formation of it’s sheet like structure. These proteins are not at all soluble in water and can only be dissolved in strong acids which serves as a distinguishing factor between other proteins and fibrous proteins.
They are used in the formation of very tough tissues to provide strength and support to other cells and tissues. They mainly form tendons, connective tissues and fibres. In fibrous proteins, the peptide chains are held together by very strong intermolecular hydrogen bonding.
Also, fibrous proteins do not de-nature easily. They are made up of single units or a unit which is repeated many times. Examples: elastin, collagen, actin, fibrin, myosin, keratin, etc.
Main Differences Between Globular Proteins and Fibrous Proteins
- Globular protein is a type of protein that is soluble and tends to be involved in metabolic functions whereas Fibrous proteins are a type of proteins that are insoluble and that helps in building up the main structural elements of the body.
- Globular proteins are soluble in water, acids and bases while Fibrous proteins are only soluble in strong acids.
- Globular proteins are spherical in shape and have a folded ball like structure whereas Fibrous proteins are long and narrow in shape like rods and wires and have a helical or sheet like structure.
- The main function of Globular proteins is the formation of cellular messengers, enzymes and amino acids whereas the main function of Fibrous proteins is formation of tough tissues. They are used in the formation of fibres, connective tissues and tendons.
- Globular proteins have a weak intermolecular force between them whereas Fibrous proteins have a strong intermolecular force between them.
Conclusion
Both globular proteins and fibrous proteins are a type of protein which helps in building tissues and repair of cells. The main difference between the two is the function they perform in the human body. The globular proteins are used in the formation of amino acids, enzymes and cellular messengers whereas the fibrous proteins are used in the formation of connective tissues, tendons and fibres.
Also, the globular proteins have a spherical shape while the fibrous proteins have a narrow strand-like shape just like rods and wires. The intermolecular force between these proteins are different as well. The globular proteins have a weak intermolecular force between each other while the fibrous proteins have a strong intermolecular force between each other.
Due to the spherical shape of globular proteins, they are able to form colloids. Thus, they get easily soluble in water, bases and acids. But, the fibrous proteins are not at all soluble in water, weak acids and weak bases. They are only soluble in strong acids. Examples of globular proteins are haemoglobin, hormones, immunoglobulin while examples of fibrous proteins are keratin, elastin, actin, etc.
References
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1063354/
- https://pubs.acs.org/doi/pdf/10.1021/ja01252a512