Globular proteins are compact, spherical proteins that are soluble in water. They are typically involved in metabolic processes and often have enzymatic functions. On the other hand, fibrous proteins are elongated, thread-like proteins that are insoluble in water. They are typically involved in structural support and provide mechanical strength to tissues and organs.
What is Globular Proteins?
Globular proteins are water-soluble proteins that are roughly spherical in shape, with a compact structure that is stabilized by hydrophobic interactions and hydrogen bonds.
Functions of Globular Proteins
- Globular proteins have multiple functions as they are used to form enzymes, cellular messengers, amino acids but fibrous proteins act only as structural proteins.
- Globular proteins are highly branched or coiled structures and are majorly responsible for transportation of vital nutrients like oxygen through hemoglobin.
- Globular proteins are the major source of hemoglobin, immunoglobulins, insulin and milk-protein casein.
- They also are involved in the formation of amino acids which are basic building blocks of all proteins.
- They are needed for the formation of chemical messengers like hormones in the body.
- They are essential for the formation of transporters of other particles through the membrane.
- Myoglobin is another example of globular protein which is the chief protein found in muscles.
Structure of Globular Proteins
Globular protein molecule has a structure of 4 levels:
- Primary − A sequence of amino acids
- Secondary − A spring-shaped helix made of the sequence of amino acids.
- Tertiary − A string of the spring-shaped helixes made of the sequence of amino acids
- Quaternary − A bundle of the string of the spring-shaped helixes made of the sequence of amino acids
What is Fibrous Protein?
Fibrous proteins are water-insoluble proteins that have a long, extended shape, with a repeating pattern of amino acid residues that form a structural unit.
Functions of Fibrous Protein
- Fibrous proteins are needed for the formation of tough structures like connective tissue, tendons and fibers of the muscle.
- Collagen is a major component of all our connective tissues.
- Fibroin is a fibrous protein which is used to produce silk by silkworms and webs of spider.
- Fibrous proteins are responsible for the production of the movements of the muscles and tendons at a joint.
Structure of Fibrous Proteins
- Fibrous proteins have primary and secondary structures. They are made up of a single unit or structure which is repeated multiple times.
- Fibrous proteins are highly resistant to digestion by enzymes and are extremely tensile.
- Fibrous proteins are also called as scleroproteins.
- Fibrous proteins are elongated strand-like structures and are usually present in the form of rods or wires.
Difference Between Globular and Fibrous Protein
Characteristic |
Globular Protein |
Fibrous Protein |
| Structure | Its structure is unstable when it is exposed to environmental changes such as heat, pH value change, etc. | Its structure is mostly rigid, unaffected due to environmental changes. |
| Solubility | They are soluble in water. | They are not soluble in water. |
| Shape | Usually long and narrow in shape | Typically spherical in shape |
| Function | To carry out almost all cell functions in the body. | To facilitate a solid structure for body parts. |
| Amino Acid | They have highly specific amino acid sequence. | These proteins have repetitive sequence of amino acid. |
Conclusion
Proteins are classified based on their structural characteristics. Globular and fibrous proteins are both required for proper cell function. We also know that they differ in some ways, such as amino acid sequence, molecular shape, water solubility, and sensitivity to environmental factors such as body temperature.
Frequently Asked Questions (FAQs) on Globular and Fibrous Protein
Q1. What are some examples of globular proteins?
Ans: Some examples of globular proteins include enzymes such as lactase and amylase, as well as transport proteins such as hemoglobin and albumin.
Q2. What are some examples of fibrous proteins?
Ans: Some examples of fibrous proteins include collagen, elastin, and keratin.
Q3. Are globular proteins more or less flexible than fibrous proteins?
Ans: Globular proteins are generally more flexible than fibrous proteins due to their compact, folded structure.
Q4. Can fibrous proteins have enzymatic functions?
Ans: While most fibrous proteins are involved in structural support, there are some fibrous proteins such as fibrinogen that have enzymatic functions.