Difference Between Peptide and Protein

Peptide and Protein, two almost similar terms but differ a lot in structure. Although they both are made up of chains of amino acids, there’s still a huge difference in their sizes.

Peptide vs Protein 

The main difference between peptide and protein is that peptide is considered as a sequence of amino acids, which is regarded as a smaller one with a simpler structure. Protein is a polypeptide that means many peptides join together to form a protein. It is a complex structure and contains primary to the quaternary structure. 

Peptide vs Protein

It is used to connect the chain of amino acids through a bond called a peptide bond. The major function is to regulate the activities of another molecule, especially protein. 

Proteins are divided into primary, secondary, tertiary, and quaternary structures and consist of a single chain of polypeptides. The main process carried by protein is the formation of important structures in the body such as muscle, cartilage, hair, etc.

Comparison Table Between Peptide and Protein

Parameters of ComparisonPeptideProtein
Type of chainShorter chain consisting of amino acidsLarger chain of amino acids
AbsorptionEasier for the body in the absorption process because it is smaller in sizeBeing a complex structure it is not that easy to be absorbed
Amino acid typeComprises both essential as well as naturally occurring amino acidsContains twenty amino acids which are called essential amino acids
Type of StructureSomewhat like a straight chain of amino acids, the primary structureIt consists of the primary, secondary, tertiary, and quaternary structure

What is Peptide?

The peptide is a type of molecule which is naturally occurring. It is found in all organisms and carries out a lot of functions. 

Formation of peptide 

  • By transcription of genetic code’s sequence.
  • mRNA carries the given code for a peptide.
  • The mRNA gives reading which is joined together to form a single molecule joined by a peptide bond.

Types of peptide

Amino acids are like letters. As letters join together to form words, in the same way, amino acids can be joined together to form a variety of molecules.

According to Numbers, it is divided into mono, di, tri, tetra to oxytocin containing nonapeptide that is 9 and decapeptide with 10 amino acids which are angiotensin. 

It is divided into plant peptide, antibiotic peptide, fungal peptide, vaccine peptide according to function and source. 

Uses of peptides include 

  • Repairing muscles.
  • Some studies suggest that peptides are also helpful in losing weight.
  • Acting as antioxidants.

The skin is made firm and bright. It can be applied to skin both in the morning and night, and before applying it to the face, a facial peel should be done.

What is Protein?

Protein is one of those three primary macromolecules needed by our diet. Nowadays, there are various medicine supplements bars to provide extra protein.

It is also known as the backbone of our body because it is the pillar of our body and can be found in every cell of the body. They are made up of long chains of amino acids attached in a simple to complex structure.

Sources – Some of the sources of protein are seafood, whole grains, eggs, beans, and peas which come in legumes. There are also soy products and various nuts and seeds.

According to the Food development authority, an adult should take 50gm protein daily if they are taking a 2000 calorie diet. These proteins are a source of calories also.  

Functions of protein 

  • Gives a better vision 
  • Healthy muscles and bones 
  • Growth and development 

Main Differences Between Peptide and Protein

  1. Peptide bonds occur in amino acids, but in the polypeptide chain, whereas peptides are more than 50, there are hydrogen as well as disulfide bonds also. 
  2.  Peptides comprise both the essential as well as the naturally occurring amino acids, whereas protein contains only the 20 essential amino acids.
Difference Between Peptide and Protein


Peptide and protein both are strings of amino acids and are joined by peptide bonds. It is just that the amino acid number is less than 50 that is a peptide, and if the number exceeds 50, it is a protein.

Hemoglobin which is found in red blood cells, is a polypeptide and contains more than 100 amino acids, and is a long chain of amino acids.

The main reason is that when peptide breaks down it breaks into amino acids and those amino acids act as food. It can be chemically synthesized in comparison to proteins, whereas proteins are used as antibodies in Cancer patients.


  1. https://www.sciencedirect.com/science/article/pii/S0196978110004389
  2. https://pubs.acs.org/doi/full/10.1021/cr9900026

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