Difference Between Globular and Fibrous Protein

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Fibrous and Globular Proteins

Protein is present abundantly in our body. They are large size compounds formed by amino acids. These amino acids are attached to each other in a long chain-like structure to form a protein. Protein has a very short life, and its half-life is dependent upon its functions. Proteins are polymers or macromolecules made up of smaller structural units.

Most functions in our body occur due to the presence of protein. Different types of protein help in the smooth functioning of our body. Processes like DNA replication, transporting molecules, providing structural balance to cells and organisms, response to stimuli and metabolic reactions. Proteins are differentiated upon the sequence of amino acids.

Proteins can be classified upon the basis of structure and function. The four different levels of a protein structure are - primary, secondary, tertiary and quaternary structure. On the basis of function, it can be classified as fibrous protein, globular protein and membrane protein. We will discuss the difference between fibrous and globular proteins in this module. Also, we will try to understand the different types of protein.

Difference Between Fibrous Protein and Globular Protein

Protein is present in our hairs, nails, in our muscles and haemoglobin present in our red blood cells. Depending upon the functions of protein we differentiate protein into three types- globular, fibrous and membrane proteins. These proteins help in the normal functioning of the body. Let us discuss these three types of proteins in detail.

  • Globular Proteins: 

Globular proteins have a spherical like structure. These are one of the most abundant types of proteins. Globular proteins help in bodily functions. Globular proteins are mostly soluble in water and form colloids. They act as enzymes, messengers, transporters, regulators and sometimes also as a structural protein. Haemoglobin is a common globular protein.

  • Fibrous Proteins: 

Fibrous proteins are made up of sheet-like filamentous structures. Fibrous proteins have low solubility in water. These types of protein provide protection and function in the structural role by forming connective tissues, tendons and muscle fibres. Fibrous proteins are made up of regular amino acid sequences. A most common form of fibrous protein is collagen.

  • Membrane Proteins: 

Membrane proteins as the name suggests are commonly found and are present in the membranes. They interact with these biological membranes and therefore are the target of medicinal drugs. These help in providing receptor signals between the internal and external environments of the cell. Also, they help in transporting molecules and allow interaction between molecules. Types of membrane proteins include integral membrane protein and peripheral membrane protein.

What is the Difference Between Fibrous Protein and Globular Protein?

Globular protein and fibrous protein are different types of protein which are essential in the proper functioning of a human body. While globular helps in a variety of functions, fibrous proteins are involved with providing structural stability to the organism. Proteins are made up of amino acids strands.   

Globular protein and fibrous protein have some differentiating points. These are due to changes in the structure of the protein and the sequence of amino acids. The point of difference between fibrous protein and globular protein is given below:

Fibrous Protein

Globular Protein

Fibrous proteins are made up of long and narrow sheet-like structure which are filamentous 

Globular proteins are round or spherical.

Fibrous protein help in providing protection and play a structural role in organisms

Globular protein act as a functional protein performing functions like enzymes, as messengers, in the transportation of molecules and regulators

Fibrous proteins are made up of regular amino acid strands

The amino acid sequence is irregular in globular proteins

Fibrous proteins are less sensitive to any changes in temperature or pH

Globular proteins are sensitive to any changes in pH, temperature etc.

Fibrous proteins are not soluble in water

Globular proteins are generally soluble in water and form colloids

Examples of fibrous protein are- Collagen, fibrin, keratin, actin etc

Examples of globular proteins are - Haemoglobin, insulin, myoglobin etc

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FAQ (Frequently Asked Questions)

1. Explain the Different Functions of Globular Proteins.

Ans: Globular proteins are functional proteins which are involved in a variety of bodily functions. Globular proteins are made up of irregularly arranged amino acid sequences. Globular proteins are soluble in water and form corresponding colloids. Other types of protein, fibrous and membrane are insoluble in water. 

Globular proteins are commonly found proteins which are spherical or round. This shape is influenced by the tertiary structure of the protein. Globular proteins have a variety of roles:

  • Globular proteins act as enzymes and catalyze various organic reactions taking place inside the organism specifically targeting the reaction under mild conditions.

  • Hormones such as insulin act as messengers of information about biological processes.

  • Globular proteins help in regulating different biological processes taking place inside the body.

  • They also act as transporters of molecules through membranes.

  • Globular proteins also work as structural proteins. These are soluble in water but form long and stiff polymers.

2. Explain the Differences in the Structures of the Protein.

Ans: The three-dimensional structure of the protein is essential to its function. The variety of functions that take place in a body are possible due to the presence of protein. These varying properties of proteins are a function of their different structures-

  • Primary structure- The amino acid sequence present in the protein defines its primary structure. The unique function of the protein is due to this sequence of amino acids bonded together by peptide bonds.

  • Secondary structure - The secondary structure forms an irregular substructure of the protein. Two common arrangements are- alpha helix which adopts a spiral shape and beta-sheet which is made up of side by side arranged amino acids.

  • Tertiary structure - The overall three-dimensional structure of the protein is defined by the tertiary structure. Intermolecular forces exist to provide stability between these molecules.

  • Quaternary Structure - It defines the specific interaction and orientation of the protein structure.