Reference

Amino acid reference table

Name: Amino acid reference table
Creator: Revial Labs Research
License: https://creativecommons.org/licenses/by/4.0/

The 20 standard amino acids at a glance

Amino acid	3-letter	1-letter	Residue mass, mono (Da)	Residue mass, avg (Da)	Side-chain class	Side-chain pKa	Hydropathy
Glycine	Gly	G	57.02146	57.0519	Nonpolar, aliphatic	–	-0.4
Alanine	Ala	A	71.03711	71.0788	Nonpolar, aliphatic	–	1.8
Proline	Pro	P	97.05276	97.1167	Nonpolar, aliphatic	–	-1.6
Valine	Val	V	99.06841	99.1326	Nonpolar, aliphatic	–	4.2
Leucine	Leu	L	113.08406	113.1594	Nonpolar, aliphatic	–	3.8
Isoleucine	Ile	I	113.08406	113.1594	Nonpolar, aliphatic	–	4.5
Methionine	Met	M	131.04049	131.1926	Nonpolar, aliphatic	–	1.9
Phenylalanine	Phe	F	147.06841	147.1766	Aromatic	–	2.8
Tyrosine	Tyr	Y	163.06333	163.1760	Aromatic	10.07	-1.3
Tryptophan	Trp	W	186.07931	186.2132	Aromatic	–	-0.9
Serine	Ser	S	87.03203	87.0782	Polar, uncharged	–	-0.8
Threonine	Thr	T	101.04768	101.1051	Polar, uncharged	–	-0.7
Cysteine	Cys	C	103.00919	103.1388	Polar, uncharged	8.18	2.5
Asparagine	Asn	N	114.04293	114.1038	Polar, uncharged	–	-3.5
Glutamine	Gln	Q	128.05858	128.1307	Polar, uncharged	–	-3.5
Lysine	Lys	K	128.09496	128.1741	Positively charged	10.53	-3.9
Arginine	Arg	R	156.10111	156.1875	Positively charged	12.48	-4.5
Histidine	His	H	137.05891	137.1411	Positively charged	6.00	-3.2
Aspartate	Asp	D	115.02694	115.0886	Negatively charged	3.65	-3.5
Glutamate	Glu	E	129.04259	129.1155	Negatively charged	4.25	-3.5

How to use this table

Residue masses are the masses of each amino acid within a chain, after losing water to form peptide bonds. To get a peptide's mass, add the residue masses and then one water (18.01056 Da monoisotopic, 18.0153 Da average), or use the peptide mass calculator.
Leucine and isoleucine have identical masses, so a basic mass measurement can't tell them apart.
Side-chain pKa values are typical textbook values for free amino acids. In peptides they shift with neighbouring residues and conditions, and published sets differ slightly.
Hydropathy uses the Kyte–Doolittle scale: positive values are hydrophobic, negative values hydrophilic. In reverse-phase HPLC, more hydrophobic peptides generally elute later. See How to read an HPLC chromatogram.
Glycine is the only standard amino acid that isn't chiral. All the others exist in L and D forms; see D-amino acids and peptidomimetics.

Kyte J, Doolittle RF. A simple method for displaying the hydropathic character of a protein. J Mol Biol 1982;157:105–132. doi:10.1016/0022-2836(82)90515-0 · PMID: 7108955
Steen H, Mann M. The ABC’s (and XYZ’s) of peptide sequencing. Nat Rev Mol Cell Biol 2004;5:699–711. doi:10.1038/nrm1468 · PMID: 15340378