Amino Acid Structure Chart and Reference Table

Amino acids are the backbone of peptides and proteins. All amino acids contain both amino and carboxylic acids, and in certain cases, side chains.

The properties of amino acids are determined by the functional substituents linked on the side chains, which are most commonly referred to as R groups. In the amino acid chart listed here, we describe the 20 standard residues found in nature, along with the universal genetic codes.

Aliphatic Amino Acids with Hydrophobic Side Chain
Name	3-Letter Symbol	1-Letter Symbol	Formula	Molecular Weight	Isoelectric Point	Structure
Alanine	ALA	A	C3H7N1O2	89.09	6.00
Isoleucine	ILE	I	C6H13N1O2	131.17	5.94
Leucine	LEU	L	C6H13N1O2	131.17	5.98
Valine	VAL	V	C5H11N1O2	117.15	5.96

Aromatic Amino Acids with Hydrophobic Side Chain
Name	3-Letter Symbol	1-Letter Symbol	Formula	Molecular Weight	Isoelectric Point	Structure
Phenylalanine	PHE	F	C9H11N1O2	165.19	5.48
Tryptophan	TRP	W	C11H12N2O2	204.23	5.89
Tyrosine	TYR	Y	C9H11N1O3	181.19	5.66

Amino Acids with Neutral Side Chain
Name	3-Letter Symbol	1-Letter Symbol	Formula	Molecular Weight	Isoelectric Point	Structure
Asparagine	ASN	N	C4H8N2O3	132.12	5.41
Cysteine	CYS	C	C3H7N1O2S1	121.16	5.02
Glutamine	GLN	Q	C5H10N2O3	146.15	5.65
Methionine	MET	M	C5H11N1O2S1	149.21	5.74
Serine	SER	S	C3H7N1O3	105.09	5.68
Threonine	THR	T	C4H9N1O3	119.12	5.64

Amino Acids with Positive Charged Side Chain
Name	3-Letter Symbol	1-Letter Symbol	Formula	Molecular Weight	Isoelectric Point	Structure
Arginine	ARG	R	C6H14N4O2	174.2	11.15
Histidine	HIS	H	C6H9N3O2	155.16	7.47
Lysine	LYS	K	C6H14N2O2	146.19	9.59

Amino Acids with Negative Charged Side Chain
Name	3-Letter Symbol	1-Letter Symbol	Formula	Molecular Weight	Isoelectric Point	Structure
Aspartic Acid	ASP	D	C4H7N1O4	133.1	2.77
Glutamic Acid	GLU	E	C5H9N1O4	147.13	3.22

Unique Amino Acids
Name	3-Letter Symbol	1-Letter Symbol	Formula	Molecular Weight	Isoelectric Point	Structure
Glycine	GLY	G	C2H5N1O2	75.07	5.97
Proline	PRO	P	C5H9N1O2	115.13	6.30