The key difference between fibrous and globular proteins is that fibrous proteins are long strand-like proteins that are insoluble in water, weak acids, and weak bases while globular proteins are proteins with a spherical shape that are soluble in water, acids, and bases.
Proteins are one of the important macromolecules of living organisms. They contain one or more polypeptide chains built from amino acids. Thus, the amino acid is the functional and structural unit of proteins. During the synthesis of proteins, polypeptide chains fold with each other to form specific three-dimensional (3D) structures. Depending on the nature of these three- dimensional structures, there are two types of proteins as globular proteins and fibrous proteins. These two types of proteins are equally important as they carry out many functions in the body.
CONTENTS
1. Overview and Key Difference
2. What are Fibrous Proteins
3. What are Globular Proteins
4. Similarities Between Fibrous and Globular Proteins
5. Side by Side Comparison – Fibrous vs Globular Proteins in Tabular Form
6. Summary
What are Fibrous Proteins?
Fibrous proteins are water-insoluble proteins that form various types of structures such as rigid, rod-like, sheet-like etc. Furthermore, they are insoluble in weak acids and bases. As the name implies, most fibrous proteins are extensively cross-linked to form fibrous structures.
Figure 01: Keratin
Fibrous proteins mainly help in supporting functions such as providing tensile strength, elasticity, rigidity, and structural functions such as forming membrane structures, scaffold structures inside cells, etc. Moreover, fibrous proteins are present in skin, hair, nuclear membrane, red blood cell membranes, etc. Some examples of fibrous proteins are F-actin, collagen and elastin, desmin, fibroin, and keratin.
What are Globular Proteins?
Globular proteins are water-soluble proteins with spherical shapes and irregular amino acid sequences. The polypeptide chains are folded in to form their shapes, and this shape is specific for each globular protein type. The water solubility of globular proteins enables them to transport through blood and other body fluids to various locations that require their action.
Figure 02: Globular Protein
Globular proteins mainly help in carrying many chemical reactions, which enable organisms to convert outside energy sources to usable energy form. These proteins also act as catalysts for thousands of chemical reactions occurring in the body. Moreover, globulin proteins involve in glucose metabolism, oxygen storage in muscles, oxygen transport in blood, immune responses, etc. Some examples of globular proteins are insulin, myoglobin, hemoglobin, transferrin, and immunoglobulins.
What are the Similarities Between Fibrous and Globular Proteins?
- Fibrous and globular proteins are types of proteins composed of amino acids.
- Both serve as structural proteins as well as functional proteins.
- Also, both have primary and secondary structures.
- Furthermore, they are essential molecules for the growth and development of living organisms.
What is the Difference Between Fibrous and Globular Proteins?
The key difference between fibrous and globular proteins is that the fibrous proteins are insoluble in water, weak bases, and weak acids whereas, globular proteins are soluble in water, bases, and acids. Also, a further difference between fibrous and globular proteins is that the fibrous proteins are elongated strand like proteins while globular proteins are spherical proteins. Moreover, functionally, the difference between fibrous and globular proteins is that the fibrous proteins help in structural functions such as providing support and protection, etc, while globular proteins are responsible for certain metabolic functions such as catalysis, transport, and regulation, etc. Thus
Additionally, globular proteins often have several types of secondary structures, whereas fibrous proteins contain a single type of secondary structure. Hence, this is also a difference between fibrous and globular protein. Another difference between fibrous and globular proteins is that the number of different types of globular proteins is higher than that of fibrous proteins. Being the most abundant protein in the human body, fibrous proteins have a higher total mass than globular proteins. Thus, this is one difference between fibrous and globular proteins.
Examples for fibrous proteins are keratin and collagen, whereas examples for globular proteins are hemoglobin and myoglobin. Moreover, globular proteins have much weaker secondary and tertiary bonds than fibrous proteins; thus, globular proteins denature more easily than fibrous proteins. So, this is also a difference between fibrous and globular proteins.
Summary – Fibrous vs Globular Proteins
Fibrous and globular proteins are two types of proteins present in our body. Fibrous proteins are elongated strand like protein On the other hand, globular proteins are spherical in shape. Furthermore, fibrous proteins are insoluble in water, while globular proteins are soluble in water. Moreover, globular proteins act as catalysts of biochemical reactions while fibrous proteins provide structural functions. Compared to globular proteins, fibrous proteins are abundant in our body. This summarizes the difference between fibrous and globular proteins.
Reference:
1. “Structural Biochemistry/Proteins/Fibrous Proteins.” Development Cooperation Handbook/Guidelines/How to Manage Programmes for a Learning Organization That Is Projectized and Employee Empowering – Wikibooks, Open Books for an Open World, Wikimedia Foundation, Inc., Available here.
Image Courtesy:
1. “Hierarchical structure of hair in the cortex and cuticle” By Yang F, Zhang Y, Rheinstädter MC – [1] (CC BY 4.0) via Commons Wikimedia
2. “1GZX Haemoglobin” By Zephyris at the English language Wikipedia (CC BY-SA 3.0) via Commons Wikimedia