AAT Bioquest

What are the differences between peptide and protein?

Posted June 6, 2023


Peptide and protein are two types of structures composed of amino acids. There are several differences between the two.

Basis Of Differentiation




Is a short chain of amino acids that are connected to one another in a sequence by a peptide bond

Is a longer chain of amino acids 

Number of amino acids

May contain up to 50 or fewer amino acids 

May contain more than 50 amino acids

Types of amino acids 

Is composed of essential amino acids as well as other naturally-occurring amino acids

Is composed of 20 essential amino acids


Is a simple structure that is made up of a polypeptide backbone to which are attached the amino-acids specific side chains, the R group

Is a complex molecule made up of one or more polypeptide chains folding into secondary, tertiary or quaternary structure, which is held stable by 3 types of weak non-covalent bonds – ionic bonds, hydrogen bonds, and van der Waal bonds


Composed of both essential amino acids and other naturally-occurring amino acids

Composed only of 20 essential amino acids


Plays a key role in regulating activities of other molecules, particularly proteins

Serves as enzymes, structural molecules, and hormones

Additional resources

Biochemistry, Peptide

Peptide and Protein Molecular Weight Calculator

Peptide and Oligonucleotide Labeling

Tide Quencher™ 1 succinimidyl ester [TQ1 SE]