Amino Acid 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.

Aliphatic Amino Acids with Hydrophobic Side Chain

Name3-Letter Symbol1-Letter SymbolFormulaMolecular WeightIsoelectric Point
AlanineALAAC3H7N1O289.096.00
IsoleucineILEIC6H13N1O2131.175.94
LeucineLEULC6H13N1O2131.175.98
ValineVALVC5H11N1O2117.155.96

Aromatic Amino Acids with Hydrophobic Side Chain

Name3-Letter Symbol1-Letter SymbolFormulaMolecular WeightIsoelectric Point
PhenylalaninePHEFC9H11N1O2165.195.48
TryptophanTRPWC11H12N2O2204.235.89
TyrosineTYRYC9H11N1O3181.195.66

Amino Acids with Neutral Side Chain

Name3-Letter Symbol1-Letter SymbolFormulaMolecular WeightIsoelectric Point
AsparagineASNNC4H8N2O3132.125.41
CysteineCYSCC3H7N1O2S1121.165.02
GlutamineGLNQC5H10N2O3146.155.65
MethionineMETMC5H11N1O2S1149.215.74
SerineSERSC3H7N1O3105.095.68
ThreonineTHRTC4H9N1O3119.125.64

Amino Acids with Positive Charged Side Chain

Name3-Letter Symbol1-Letter SymbolFormulaMolecular WeightIsoelectric Point
ArginineARGRC6H14N4O2174.211.15
HistidineHISHC6H9N3O2155.167.47
LysineLYSKC6H14N2O2146.199.59

Amino Acids with Negative Charged Side Chain

Name3-Letter Symbol1-Letter SymbolFormulaMolecular WeightIsoelectric Point
Aspartic AcidASPDC4H7N1O4133.12.77
Glutamic AcidGLUEC5H9N1O4147.133.22

Unique Amino Acids

Name3-Letter Symbol1-Letter SymbolFormulaMolecular WeightIsoelectric Point
GlycineGLYGC2H5N1O275.075.97
ProlinePROPC5H9N1O2115.136.30

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

Amino Acids Structure Abbr (3) Abbr (1) Enzymes Codon Class Hydrophobicity (pH 7) Freq. in Proteins (max. 10) pKa pI Chemical formula Molar massIUPAC nameOther namesAppearanceDensityMelting pointSolubility in water
Alanine O O N H H H H H H H AlaAAlanine AminotransferaseGCT, GCC, GCA, GCGAliphatic417.52.346.00C3H7NO289.094Alanine2-Aminopropanoic acidwhite 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 ArgRArginaseCGT, CGC, CGA, CGG, AGA, AGGBasic-145.02.1710.76C6H14N4O2174.204(S)-2-Amino-5-guanidinopentanoic acid2-Amino-5-guanidinopentanoic acidWhite 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; AsparaginaseAAT, AACAmidic-284.52.025.41C4H8N2O3132.119Asparagine2-Amino-3-carbamoylpropanoic acidwhite 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 ProteinaseGAT, GACAcidic-555.01.882.77C4H7NO4133.1032-Aminobutanedioic acidAminosuccinic acid; Asparagic acid; Asparagini…colourless 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 PeptidaseTGT, TGCSulfur-containing492.01.965.07C3H7NO2S121.150Cysteine2-Amino-3-sulfhydrylpropanoic acidwhite 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 DecarboxylaseGAA, GAGAcidic-316.52.193.22C5H9NO4147.1302-Aminopentanedioic acid2-Aminoglutaric acidwhite 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 SynthetaseCAA, CAGAmidic-104.02.175.65C5H10N2O3146.146GlutamineL-Glutamine; (levo)glutamide; 2,5-Diamino-5-ox…White 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-MethyltransferaseGGT, GGC, GGA, GGGAliphatic07.02.345.97C2H5NO275.0672-aminoacetic acid2-Aminoethanoic acid, GlycocollWhite 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 PhytasesCAT, CACBasic82.01.827.59C6H9N3O2155.157Histidine2-Amino-3-(1H-imidazol-4-yl)propanoic acidcolourless 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-EpimeraseATT, ATC, ATAAliphatic995.52.366.02C6H13NO2131.175Isoleucine(2S,3S)-2-amino-3-methylpentanoic acidwaxy, 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 AminopeptidaseCTT, CTC, CTA, CTG, TTA, TTGAliphatic979.02.365.98C6H13NO2131.175Leucine2-Amino-4-methylpentanoic acidwhite 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-AminomutaseAAA, AAGBasic-236.02.189.74C6H14N2O2146.190(2S)-2,6-Diaminohexanoic acid (L-lysine); (2R)…Lysine, D-Lysine, L-lysine, LYS, h-Lys-OHcolourless 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 AminopeptidaseATGSulfur-containing742.52.285.74C5H11NO2S149.210Methionine2-amino-4-(methylthio)butanoic acidWhite 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 HydroxylaseTTT, TTCAromatic1004.01.835.48C9H11NO2165.192(S)-2-Amino-3-phenylpropanoic acidL-PhenylalanineWhite 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-HydroxlaseCCT, CCC, CCA, CCGAliphatic-465.01.996.30C5H9NO2115.132Proline; Pyrrolidine-2-carboxylic acidL-ProlineTransparent 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 RacemaseTCT, TCC, TCA, TCG, AGT, AGCHydroxylic-57.52.215.68C3H7NO3105.093Serine2-Amino-3-hydroxypropanoic acidwhite 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 AldolaseACT, ACC, ACA, ACGHydroxylic136.02.095.60C4H9NO3119.120Threonine2-Amino-3-hydroxybutanoic acidcolourless 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-DioxygenaseTGGAromatic971.52.835.89C11H12N2O2204.229Tryptophan; (2S)-2-amino-3-(1H-indol-3-yl)prop…2-Amino-3-(1H-indol-3-yl)propanoic acidWhite 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 DecarboxylaseTAT, TACAromatic633.52.205.66C9H11NO3181.191(S)-TyrosineL-2-Amino-3-(4-hydroxyphenyl)propanoic acidwhite 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 DehydrogenaseGTT, GTC, GTA, GTGAliphatic766.52.325.96C5H11NO2117.148Valine2-Amino-3-methylbutanoic acidwhite crystalline solid1.316 g/cm3298 °C (568 °F; 571 K) (decomposition)soluble