Protein Science and Its Significance

Introduction

Proteins are known as the basic body-building macromolecules in our body. Since they are required in more quantity in our body like carbohydrates and lipids, they are called macromolecules. Proteins are made up of monomeric units called amino acids to form polymeric proteins. So, we can say that amino acids are the building blocks of proteins.

Proteins form the essential part of every cell and are important for growth and repair are form the enzymes in our body. They mediate virtually every process that takes place in a cell, exhibiting an almost endless diversity of functions. Study of proteins, their structure, properties, mechanism of action and their functions in an organism is called protein science.

Properties of Proteins

It is very important to understand the physical and chemical properties of proteins for their isolation and synthesis in vivo and in vitro.

Physical Properties of Proteins

Water Solubility

Primary and secondary structures are comparatively more soluble due to the formation of hydrogen bonds compared to tertiary structures.

Denaturing and Renaturing of Proteins

Denaturation is the process by which a protein loses its secondary and tertiary structure but there is no change in its primary structure. Denaturation is brought about by heat or urea which causes the breaking of the peptide bond.

When the denaturing agent is removed proteins get back to their original structure this property of proteins is called denaturing.

Coagulation

The process by which insoluble aggregates are formed when protein is subjected to denaturation by heat is called coagulation. Albumins and globulins are mostly prone to coagulation.

Isoelectric Point

It can be defined as the pH at which the number of cations is equal to the number of anions. This property is very useful in the extraction of proteins.

Post-Translational Modification

After the proteins are synthesized in ribosomes proteins undergo various modifications like glycosylation, phosphorylation, acetylation, etc. These modifications alter the protein function.

Chemical Properties of Proteins

Ninhydrin Test

Appearance of violet colour when protein is heated with ninhydrin indicates the presence of α-amino acids.

Biuret Test

A violet color is formed when sodium hydroxide and copper sulfate is added to the protein solution which indicates the presence of a peptide bond.

Structure of Proteins

Proteins are made up of amino acids that are joined end to end by peptide bonds, this chain like structure is known as polypeptide. The arrangement of amino acid residues in a polypeptide chain determines its function.

There are four levels of organization in protein structure −

• Primary structure

• Secondary structure

• Tertiary structure

• Quaternary structure

Primary Structure

It consists of amino acids which are joined together in the form of the polypeptide chain, in which amino acids are linked to one another by peptide bonds. The N-terminal amino group and C-terminal carboxyl group are responsible for the charges on the polypeptide chain.

Secondary Structure

The regular repeating pattern of the hydrogen bond between the atoms of the polypeptide chain leads to the formation of a secondary structure. The folding pattern of the secondary structure can be of two types −

• Alpha helix (α-helix)

• Beta helix (β- helix)

Tertiary Structure

It is the three-dimensional structure of the protein, which occurs due the non-covalent interactions like electrostatic interactions, hydrogen bonds, hydrophobic interaction, etc. Mostly these interactions are responsible for the hydrophobic properties of certain proteins. In addition to the non-covalent interaction covalent disulfide bonds are also found in the tertiary structure.

Quaternary Structure

This organization contains more than one polypeptide chain and represents the spatial arrangement of various subunits in a protein.

Types of Proteins

Based on the shape, structure, chemical properties and solubility proteins have been divided into three types −

• Simple proteins.

• Conjugated proteins.

• Derived proteins.

Simple Proteins

These proteins on hydrolysis give only amino acids as they consist of only amino acids. They are of two types namely- Fibrous and globular proteins.

Conjugated Proteins

In addition to amino acids, they also contain non-proteinaceous groups like lipids, phosphate groups, or metal ions.

Derived Proteins

When simple and conjugated proteins are subjected to physical or chemical treatment, derived proteins are obtained. For example, peptones, protease, etc.

Significance of Protein Science

Proteins are involved in nearly all the vital activities in an organism and their functions are endless. Knowing about proteins is very important and it has the following applications −

• Proteins form all the enzymes in the body, they also form other components of the body like antibodies and hormones. knowledge about these proteins can be used for their synthesis in large scale.

• Some metalloproteins help in the transport of oxygen and carbon dioxide in the body.

• Proteins like thrombin, fibrinogen help in blood clotting. They also play important role in providing immunity to our body through antibodies.

• Proteins like actin and myosin help in movement and locomotion. They also help in storage like in case of albumin.

• Proteins play a crucial role in expression of the genetic information across generations.

• Plasma proteins always make up the balance between the volumes of circulating blood and interstitial fluid by a process called homeostasis.

Conclusion

Protein science is all about knowing structure, function and properties of the proteins in detail. This study helps in the knowing various mechanisms that proteins are involved in, various proteins formed in the body, their action and the conditions related to their deficiency. All these studies provide insights into the development of various proteins outside the body on a large scale.