20 Amino Acids


Amino acids are organic compounds containing an amino group (-NH2) and a carboxyl group (-COOH). This is the general structure of an amino acid:

General Amino Acid Structure

where R is the side chain functional group that distinguishes one amino acid from another.

This is a table of the 20 amino acids derived from proteins. The table contains the amino acid’s name, common abbreviation and symbol, linear structure and skeletal structure.

 Name Symbol Linear StructureSkeletal Structure
Alanineala ACH3-CH(NH2)-COOHAlanine Structure
Argininearg RHN=C(NH2)-NH-(CH2)3-CH(NH2)-COOHArginine Structure
Asparagineasn NH2N-CO-CH2-CH(NH2)-COOHAsparagine Structure
Aspartic Acidasp DHOOC-CH2-CH(NH2)-COOHAspartic Acid Structure
Cysteinecys CHS-CH2-CH(NH2)-COOHCysteine Structure
Glutamic Acidglu EHOOC-(CH2)2-CH(NH2)-COOHGlutamic Acid Structure
Glutaminegln QH2N-CO-(CH2)2-CH(NH2)-COOHGlutamine Structure
Glycinegly GNH2-CH2-COOHGlycine Structure
Histidinehis HNH-CH=N-CH=C-CH2-CH(NH2)-COOHHistidine Structure
Isoleucineile ICH3-CH2-CH(CH3)-CH(NH2)-COOHIsoleucine Structure
Leucineleu L(CH3)2-CH-CH2-CH(NH2)-COOHLeucine Structure
Lysinelys KH2N-(CH2)4-CH(NH2)-COOHLysine Structure
Methioninemet MCH3-S-(CH2)2-CH(NH2)-COOHMethionine Structure
Phenylalaninephe FPh-CH2-CH(NH2)-COOHPhenylanaline Structure
Prolinepro PNH-(CH2)3-CH-COOHProline Structure
Serineser SHO-CH2-CH(NH2)-COOHSerine Structure
Threoninethr TCH3-CH(OH)-CH(NH2)-COOHTyrosine Structure
Tryptophantrp WPh-NH-CH=C-CH2-CH(NH2)-COOHTryptophan Structure
Tyrosinetyr YHO-Ph-CH2-CH(NH2)-COOHTyrosine Structure
Valineval V(CH3)2-CH-CH(NH2)-COOHValine Structure

Amino acids are often grouped by the chemistry of the side chain. These groups are polar-uncharged, polar-charged and non-polar.

Eight of the 20 amino acids are polar-uncharged: Asparagine, cysteine, glutamine, histidine, serine, threonine, tryptophan and tyrosine.

Eight of the 20 amino acids are non-polar: alanine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, and valine.

The final four are polar-charged: arginine, aspartic acid, glutamic acid, and lysine.

A downloadable study sheet of this information is available here.