AAT Bioquest

Amino Acid Reference Chart

Amino acids are the building blocks that make up all proteins, polypeptides and peptides. Each amino acid consists of a central carbon, known as the α-carbon, to which an amino group (-NH2), an acidic carboxyl group (-COOH) and an organic side chain (-R group) are bound. The R group, which differs for each amino acid, will determine its structure, polarity and pH.

Refer to chart below to explore structures, properties and types for each of the 20 standard amino acids.

Amino Acids
Abbr (3)
Abbr (1)
Hydrophobicity (pH 7)
Freq. in Proteins (max. 10)
Chemical formula
Molar mass
IUPAC name
Other names
CAS Number
Melting point
Solubility in water
Alanine O O N H H H H H H H AlaAAlanine Aminotransferase13803, 13802, 13826, 13825GCT, GCC, GCA, GCGAliphatic417.52.346.00C3H7NO289.094Alanine2-Aminopropanoic acid338-69-2; 56-41-7; 302-72-7;InChI=1S/C2H4NH2COOH/c1-2(4)3(5)6/h2H,4H2,1H3,...O=C(O)C(N)Cwhite powder1.424 g/cm3258 °C (496 °F; 531 K) (sublimes)167.2 g/L (25 °C)
Arginine O O N N N N H H H H H H H H H H H H H H ArgRArginase-CGT, CGC, CGA, CGG, AGA, AGGBasic-145.02.1710.76C6H14N4O2174.204(S)-2-Amino-5-guanidinopentanoic acid2-Amino-5-guanidinopentanoic acid7200-25-1; 157-06-2; 74-79-3InChI=1S/C6H14N4O2/c7-4(5(11)12)2-1-3-10-6(8)9...NC(CCCNC(N)=N)C(O)=OWhite crystals1.5±0.1 g/cm3260 °C; 500 °F; 533 K14.87 g/100 mL (20 °C)
Asparagine O O O N N H H H H H H H H AsnNAsparagine Synthetase; Asparaginase-AAT, AACAmidic- acid70-47-3InChI=1S/C4H8N2O3/c5-2(4(8)9)1-3(6)7/h2H,1,5H2...O=C(N)C[C@H](N)C(=O)Owhite crystals1.543 g/cm3234 °C (453 °F; 507 K)2.94 g/100 mL
Aspartic acid O O O O N H H H H H H H AspDAspartic Protease; Aspartic Proteinase13828, 13827, 13480GAT, GACAcidic-555.01.882.77C4H7NO4133.1032-Aminobutanedioic acidAminosuccinic acid; Asparagic acid; Asparagini...617-45-8; 56-84-8; 1783-96-6InChI=1S/C4H7NO4/c5-2(4(8)9)1-3(6)7/h2H,1,5H2,...O=C(O)CC(N)C(=O)Ocolourless crystals1.7 g/cm3270 °C (518 °F; 543 K)4.5 g/L
Cysteine S O O N H H H H H H H CysCCysteine Protease; Cysteine Peptidase-TGT, TGCSulfur-containing492.01.965.07C3H7NO2S121.150Cysteine2-Amino-3-sulfhydrylpropanoic acid52-90-4; 52-89-1InChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(...C([C@@H](C(=O)O)N)Swhite crystals or powder1.3±0.1 g/cm240 °C (464 °F; 513 K) decomposessoluble
Glutamic acid O O O O N H H H H H H H H H GluEGlutamic Acid Decarboxylase10054, 11302GAA, GAGAcidic-316.52.193.22C5H9NO4147.1302-Aminopentanedioic acid2-Aminoglutaric acidL isomer: 56-86-0; racemate: 617-65-2; D isome...InChI=1S/C5H9NO4/c6-3(5(9)10)1-2-4(7)8/h3H,1-2...l isomer: C(CC(=O)O)[C@@H](C(=O)O)Nwhite crystalline powder1.4601 (20 °C)199 °C (390 °F; 472 K) decomposes7.5 g/L (20 °C)
Glutamine O O O N N H H H H H H H H H H GlnQGlutamine Synthetase11302CAA, CAGAmidic-; (levo)glutamide; 2,5-Diamino-5-ox...56-85-9InChI=1S/C5H10N2O3/c6-3(5(9)10)1-2-4(7)8/h3H,1...O=C(N)CCC(N)C(=O)OWhite crystalline powder1.47 g/cm3 (20 °C)decomposes around 185°Csoluble
Glycine O O N H H H H H GlyGGlycine Decarboxylase Complex; Glycine Hydroxymethyltransferase; Glycine N-Methyltransferase395, 396GGT, GGC, GGA, GGGAliphatic07.02.345.97C2H5NO275.0672-aminoacetic acid2-Aminoethanoic acid, Glycocoll56-40-6InChI=1S/C2H5NH2/c3-1-2(4)5/h1,3H2,(H,4,5); Ke...C(C(=O)O)NWhite solid1.1607 g/cm3233 °C (451 °F; 506 K) (decomposition)24.99 g/100 mL (25 °C)
Histidine O O N N N H H H H H H H H H HisHHistidine Ammonia-Lyase; Histidine Decarboxylase; Histidine Acid Phytases-CAT, CACBasic82.01.827.59C6H9N3O2155.157Histidine2-Amino-3-(1H-imidazol-4-yl)propanoic acid71-00-1InChI=1S/C6H9N3O2/c7-5(6(10)11)1-4-2-8-3-9-4/h...O=C([C@H](CC1=CNC=N1)N)Ocolourless crystals1.4±0.1 g/cm3287 °C4.19g/100g @ 25 °C
Isoleucine O O N H H H H H H H H H H H H H IleIL-Isoleucine 4-Hydroxlase; Isoleucine 2-Epimerase-ATT, ATC, ATAAliphatic995.52.366.02C6H13NO2131.175Isoleucine(2S,3S)-2-amino-3-methylpentanoic acid73-32-5InChI=1S/C6H13NO2/c1-3-4(2)5(7)6(8)9/h4-5H,3,7...CC[C@H](C)[C@@H](C(=O)O)Nwaxy, shiny crystals?1.0±0.1 g/cm3285.5 °Csoluble
Leucine O O N H H H H H H H H H H H H H LeuLLeucine Dehydrogenase; Leucine Aminotransferase; Leucine Transaminase; Leucine Deacylase; Leucine Aminopeptidase13445CTT, CTC, CTA, CTG, TTA, TTGAliphatic979.02.365.98C6H13NO2131.175Leucine2-Amino-4-methylpentanoic acid61-90-5InChI=1S/C6H13NO2/c1-4(2)3-5(7)6(8)9/h4-5H,3,7...CC(C)C[C@@H](C(=O)O)Nwhite crystals1.17 g/cm3 at 20 °C293 °Csoluble
Lysine O O N N H H H H H H H H H H H H H H LysKLysine a-Ketoglutarate Reductase; I-Lysine Monooxygenase; I-Lysine Decarboxylase; Lysine Oxidase; Lysine 2,3-Aminomutase15255AAA, AAGBasic-,6-Diaminohexanoic acid (L-lysine); (2R)...Lysine, D-Lysine, L-lysine, LYS, h-Lys-OH70-54-2; 56-87-1; 923-27-3InChI=1S/C6H14N2O2/c7-4-2-1-3-5(8)6(9)10/h5H,1...NCCCCC(N)C(=O)Ocolourless crystals1.1±0.1 g/cm 3224.5 °C1.5 kg/L
Methionine S O O N H H H H H H H H H H H MetMMethionine Synthase; Methionine Aminopeptidase-ATGSulfur-containing742.52.285.74C5H11NO2S149.210Methionine2-amino-4-(methylthio)butanoic acid59-51-8; 63-68-3 (L-isomer); 348-67-4 (D-isomer)InChI=1S/C5H11NO2S/c1-9-3-2-4(6)5(7)8/h4H,2-3,...CSCC[C@H](N)C(=O)OWhite crystalline powder1.340 g/cm3281 °C (538 °F; 554 K) decomposessoluble
Phenylalanine O O N H H H H H H H H H H H PheFPhenylalanine Hydroxylase-TTT, TTCAromatic1004.01.835.48C9H11NO2165.192(S)-2-Amino-3-phenylpropanoic acidL-Phenylalanine150-30-1; 63-91-2InChI=1S/C9H11NO2/c10-8(9(11)12)6-7-4-2-1-3-5-...N[C@@H](CC1=CC=CC=C1)C(O)=OWhite crystalline powder1.34 g/cm3 at 20 °C283 °Csoluble
Proline O O N H H H H H H H H H ProPProline Dehydrogenase; Proline 3-Hydroxlase-CCT, CCC, CCA, CCGAliphatic-465.01.996.30C5H9NO2115.132Proline; Pyrrolidine-2-carboxylic acidL-Proline609-36-9; 344-25-2 (R); 147-85-3 (S)InChI=1S/C5H9NO2/c7-5(8)4-2-1-3-6-4/h4,6H,1-3H...OC(=O)C1CCCN1Transparent crystals1.35-1.38 g/cm3 at 25 °C205 to 228 °C (401 to 442 °F; 478 to 501 K)soluble
Serine O O O N H H H H H H H SerSSerine Protease; Serine Endopeptidase; Serine Racemase-TCT, TCC, TCA, TCG, AGT, AGCHydroxylic- acid56-45-1 (L-); 302-84-1 (DL-); 312-84-5 (D-)InChI=1S/C3H7NO3/c4-2(1-5)3(6)7/h2,5H,1,4H2,(H...C([C@@H](C(=O)O)N)Owhite crystals or powder1.603 g/cm3 (22 °C)246 °C (475 °F; 519 K) decomposessoluble
Threonine O O O N H H H H H H H H H ThrTThreonine Ammonia-Lyase; Threonine Deaminase; Threonine Dehydratase; Threonine Aldolase-ACT, ACC, ACA, ACGHydroxylic136.02.095.60C4H9NO3119.120Threonine2-Amino-3-hydroxybutanoic acid80-68-2; 72-19-5 (L-isomer)InChI=1S/C4H9NO3/c1-2(6)3(5)4(7)8/h2-3,6H,5H2,...C[C@H]([C@@H](C(=O)O)N)Ocolourless crystals1.3±0.1 g/cm 3256 °C (decomposes)(H2O, g/dl) 10.6(30°),14.1(52°),19.0(61°)
Tryptophan O O N N H H H H H H H H H H H H TrpWTryptophan Synthase; Tryptophan 2,3-Dioxygenase8B1012, 8B1011, 8A1012, 8A1011TGGAromatic971.52.835.89C11H12N2O2204.229Tryptophan; (2S)-2-amino-3-(1H-indol-3-yl)prop...2-Amino-3-(1H-indol-3-yl)propanoic acid73-22-3InChI=1S/C11H12N2O2/c12-9(11(14)15)5-7-6-13-10...c1ccc2c(c1)c(c[nH]2)C[C@@H](C(=O)O)NWhite crystalline powder1.4±0.1 g/cm3290.5 °CSoluble: 0.23 g/L at 0 °C, 11.4 g/L at 25 °C
Tyrosine O O O N H H H H H H H H H H H TyrYTyrosinase; Tyrosine Hydroxylase; Tyrosine Kinase; Tyrosine Decarboxylase8B0037, 8B0038, 8B0039, 8A0037, 8A0038, 8A0039, 8B0592, 8A0592, 11312, 11311, 8C0382,TAT, TACAromatic633.52.205.66C9H11NO3181.191(S)-TyrosineL-2-Amino-3-(4-hydroxyphenyl)propanoic acid60-18-4InChI=1S/C9H11NO3/c10-8(9(12)13)5-6-1-3-7(11)4...N[C@@H](Cc1ccc(O)cc1)C(O)=Owhite crystals1.46 g/cm3 at 20 °C343 °C.0453 g/100 mL
Valine O O N H H H H H H H H H H H ValVL-Valine Dehydrogenase-GTT, GTC, GTA, GTGAliphatic766.52.325.96C5H11NO2117.148Valine2-Amino-3-methylbutanoic acid0516-06-03; 72-18-4 (L-isomer); 640-68-6 (D-is...InChI=1S/C5H11NO2/c1-3(2)4(6)5(7)8/h3-4H,6H2,1...CC(C)[C@@H](C(=O)O)Nwhite crystalline solid1.316 g/cm3298 °C (568 °F; 571 K) (decomposition)soluble


This online tool may be cited as follows


"Quest Database™ Amino Acid Reference Chart." AAT Bioquest, Inc.18 Apr2024https://www.aatbio.com/data-sets/amino-acid-reference-chart-table.


AAT Bioquest, Inc. (2024April 18). Quest Database™ Amino Acid Reference Chart. AAT Bioquest. https://www.aatbio.com/data-sets/amino-acid-reference-chart-table.