Proteins Functions | Definition | Types | Structure & Examples

Protein Definition: Proteins are basically biomolecules that high molecular weight polymers, polymers unruffled of ? Amino acids.  ?-Amino acids are joined to one another by Peptide linkage.  Peptide Linkage is represented as (-CO-NH-). Proteins are the most important elements of all living organisms. Proteins comprised of Carbon (C), Hydrogen (H), Nitrogen (N), Oxygen (O) and Sulphur (S). Proteins Functions are described below :

Proteins Biochemistry

Proteins are the Macromolecules which play an integral role in the proper tackling of cells. Proteins built up of the linear polymers of amino acids. Proteins play an operational or mechanical role in Cell Cytoskeleton.

Proteins Formula:

Proteins Functions

Proteins Functions

Proteins Structure

Proteins are the Macromolecules which are Basically polymers of Amino Acids. Protein structures vary in size and structures due to the presence of several thousand to tens of amino acids. The biochemist has classified Proteins Structures into four Sub Levels:

  1. Primary Protein Structure
  2. Secondary Protein Structure
  3. Tertiary Protein Structure
  4. Quaternary Protein Structure

Proteins Functions


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1. Primary Protein Structure

Primary Proteins Structure are the simplest protein structures in which Amino Acids are arranged in sequence in the Polypeptide Chain. Each Polypeptide Chain has its own arrangement of Amino Acids in a specific manner. Each Polypeptide Chain of Amino Acids have Two Terminal:

Amino Terminal is at the left side of the Polypeptide Chain at which the free ?-amino group is present.

Carboxylic-Terminal is at the Right side of the Polypeptide Chain at which free ?- carboxyl group is present.

Proteins Functions

2. Secondary Protein Structure

In these structures, Polypeptide Chain is coiled together forming ?-Helix and ?-Pleated sheets.

In the ?-Helix adjacent to the Amino Acids, there are Hydrogen bonded Nitrogen’s and Oxygen’s are present. Proline, Glycine, and Asparagine in the ?-Helix are known as Helix Breakers.

In ? Pleated sheets, between adjacent peptide chains the hydrogen bonds present.? Pleated strands may run Parallel or Anti-parallel

Proteins Functions

Tertiary Protein Structure

Tertiary protein Structures are basically Three-Dimensional Arrangement of secondary structure polypeptide chains. Disulfide bonds are present between Amino Acids. Which help in the stabilization of its structure.

Proteins Functions

Quaternary Protein Structure

These structures are basically the arrangement of Proteins Subunits that consist of more than one Polypeptide Chains.

Proteins Functions

Types of Proteins  

Proteins are classified into three foremost clusters:

1.Simple Protein

Simple Protein is those proteins which on Hydrolysis produce only ?-Amino Acids. For Example Albumin Protein, Globulin Protein etc.

  1. Conjugated Protein

Conjugated Protein is those Proteins in which Simple Proteins, as well as Non-Protein Parts, are combined together by Peptide linkage are called as Prosthetic Groups or Conjugated Proteins. For Example Nucleo Protein, Phosphoprotein, etc.

  1. Derived Proteins

Derived Proteins are those which are basically the combination of Simple and Conjugated proteins. These proteins are usually derivative compounds of Simple Proteins and Conjugated proteins by the reaction of Alkalis, Acids or Enzymes. Derived Proteins are the end product. They are the products of partial to complete hydrolysis of Simple and Conjugated proteins. For Example Proteoses, Peptones and peptides.

Major Classes of Conjugated Proteins:

Conjugated Proteins are further subdivided into:

Proteins Functions


These are the proteins end to end with nucleic acids. For Example Histones and Protamines.


These are the protein comprising phosphoric acid in them. For Example Casein of milk.


These proteins comprehending carbohydrate. For Example Gonadotropic hormone, Mucous Glycoprotein Mucin (saliva) and Osseomucoid (bone)

Chromoprotein :

They comprise Porphyrins as per the prosthetic group. For Example Hemoglobin and Myoglobin.


They conjugated with lipids. For Example Chylomicrons


They comprised of metal atoms. For Example: Siderophilin (Fe) & Ceruloplasmin (Cu).

8 Functions of Proteins

Eight main Proteins functions are given below:

Proteins Functions

Proteins Function

Proteins functions are given below:

  1. Proteins play a vital role to perform life processes. They are the essential ingredients of Protoplasm.
  2. Enzymes are Proteins they perform the basic role of biocatalysts in chemical reactions.
  3. Proteins help as Tissues Holding the skeletal muscles.
  4. Nucleoproteins oblige as genetic characters transferring material. Also, help in transferring Traits of Inheritance.
  5. Proteins help in the transport of various compounds.
  6. Hormones are protein in nature which controls several biological functions on the body.
  7. Proteins control the Homeostatic Function of the circulating blood.
  8. Proteins are tangled in blood clotting with the collaboration of Thrombin, Fibrinogen etc.
  9. Proteins as the defense against help to treat infections by revenue of antibodies.

Proteins Examples

These are the following examples of Proteins:

  • Catalytic Proteins,
  • Amylase Protein,
  • Carbonic Anhydrase Protein
  • Nucleoproteins
  • Hormonal Proteins
  • Growth Hormone,
  • Insulin
  • Glucagon.
  • Storage proteins
  • Casein of milk Proteins,
  • Albumin Proteins.
  • Transport proteins
  • Hemoglobin.
  • Contractile Proteins
  • Defensive proteins
  • Thrombin Proteins
  • Fibrinogen Protein
  • Antibodies or Immunoglobulins
  • Structural proteins
  • Collagen,
  • Keratin
  • Toxic proteins
  • Ricin of Castor bean,
  • Diphtheria toxin
  • Botulinum toxin