AAT Bioquest

What are the differences between amino acids and proteins?

Posted June 6, 2023


Basis of differentiation

Amino acids



Are simple organic compounds that are composed of an amino group, a carboxylic group and a varying side chain denoted as R

Are large nitrogenous organic macromolecules composed of amino acid chains


Are the building blocks of proteins

Are essentially strings of amino acids


Are composed of a carboxylic acid group (COOH), an amino  (NH2), and a variable side chain (R)

Are composed of amino acids linked together by peptide bonds  

Molecular mass

Have a relatively smaller molecular mass

Are macromolecules and have a larger molecular mass 

Synthesis inside the body

Only some of the 20 amino acids can be synthesized inside the body

All the proteins are synthesized inside the body


Play a key role in protein synthesis

Serve as a structural, regulatory, and functional molecule in the body, providing cellular structure, catalyzing metabolic reactions and facilitating DNA replication


Only 20 amino acids are involved in protein synthesis in all living organisms

More than 10 million proteins are produced in biological organisms

Additional resources

Nonnatural amino acids for site-specific protein conjugation

Amino Acid Reference Chart

Amplite® Colorimetric Aspartate Aminotransferase (AST) Assay Kit