Name 3-letter code 1-letter code Neumonic pka Relative abundance (%) Volume (�^3)	Chemical Structure Click on the images below to view the 3D structures, (i.e., for link to coordinates).
Glycine Gly G Glycine - 7.5 48	flexible, seen in turns
Alanine Ala A Alanine - 9.0 67	hydrophobic, unreactive
Valine Val V Valine - 6.9 105	hydrophobic, unreactive, stiff, B-substitution
Leucine Leu L Leucine - 7.5 124	hydrophobic, unreactive
Isoleucine Ile I Isoleucine - 4.6 124	hydrophobic, unreactive, stiff, B-substitution
Methionene Met M Methionine - 1.7 124	thio-ether, only unbranched nonpolar, metal binding site
Cysteine Cys C Cysteine 8.33 2.8 86	thiol, disulfide cross-links, binds to iron and zinc, nucleophile in proteases
Proline Pro P Proline - 4.6 90	2° amine, stiff, 20% cis, seen in turns
Phenylalanine Phe F Fenylalanine - 3.5 135	hydrophobic, unreactive, polarizable, UVmax=280nm
Tryptophan Trp W tWo rings - 1.1 163	largest amino acid, hydrophobic, fluorescent, UVmax = 250nm, charge transfer
Serine Ser S Serine - 7.1 73	hydroxyl, nucleophile in serine proteases
Threonine Thr T Threonine - 6.0 93	hydroxyl, stiff, B-substitution
Tyrosine Tyr Y Tyrosine 10.13 3.5 141	aromatic, hydroxyl
Asparagine Asn N AsparagiNe - 4.4 91
Glutamine Gln Q Qutamine - 3.9 114
Lysine Lys K Before L 10.79 7.0 135	amine base, floppy
Arginine Arg R Arginine 12.48 4.7 148	guanido base, good charge couple with acid
Histidine His H Histidine 6.04 2.1 118	imidazole acid or base; pKa = pH(physio), member of catalytic triad in serine proteases, binds to copper and zinc
Aspartic Acid Asp D AsparDic 3.90 5.5 91	carboxylic acid, in active sites for cleavage of C-O bonds, member of catalytic triad in serine proteases, binds to calcium
Glutamic Acid Glu E GluEtamic 4.07 6.2 109	carboxylic acid, binds to calcium
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