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. They both are equally important for controlling various biological functions in our body. They are therefore called the functional component of cells.

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 and Protein

The peptide is a simple molecule that has a straight chain of amino acids. The number of amino acids is also less than 50. It is divided into two types are oligopeptides and polypeptides, where oligopeptides contain 2-10 amino acids, whereas the polypeptides contain 10-50 amino acids. 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. 

A polypeptide that contains more than 50 amino acids can be termed as protein. It is one of the three macronutrients found in our body and is highly important. 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. A peptide is a molecule that has 2-50 amino acids in it, and when the number exceeds 50, it is said to be a protein. 

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 

  • It helps in the hyperpigmentation process and also is beneficial in skin whitening. 
  • They help in the quick healing of wounds and fighting bacteria.
  • Repairing muscles.
  • Some studies suggest that peptides are also helpful in losing weight.
  • Acting as antioxidants.

Peptides are used as a skin booster and are also suggested by many dermatologists. There are cases where collagen productions were increased, fine lines were smoother, and there was a reduction in pores appearance. 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. Peptides are also put in masks, moisturizers, and serums. 

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. But, what is a macronutrient, and why is it important? Let’s dive in to know more about 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. 20 essential amino acids are designed in a particular way, and this structure defines the role of that particular protein. 

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. Along with it, dairy products are also a high source of protein. Vegans get less amount of protein than people who consume animal food. 

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. The amount of protein a person should have depends on their physical design also. 

Functions of protein 

  • Building and repairing the cells and tissues 
  • Blood clotting 
  • Gives a better vision 
  • Healthy muscles and bones 
  • Growth and development 

Main Differences Between Peptide and Protein

  1. Peptides consist of a shorter chain of amino acids and are connected in a simple linear structure. On the other hand, protein is a complex structure of amino acids with many functions carried in the body.
  2. The peptide is a smaller chain as it contains just 50 amino acids or even less than that, whereas protein being a polypeptide, always has an amino acid that is more than 50. 
  3. The structure of peptide is only of the primary structure, whereas protein has four types of structure ranging from primary to Quaternary. 
  4. 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. 
  5.  Peptides comprise both the essential as well as the naturally occurring amino acids, whereas protein contains only the 20 essential amino acids.


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. It is made up of two amino acid chains, one with 141 and another with 146 amino acids.  

Peptides are in research, and according to scientists, they can be the future of many industries because of being safer, more potent, and selective. 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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