Standard Amino Acids

Twenty-two amino acids are naturally incorporated into polypeptides and are called proteinogenic or natural amino acids.[9] Of these, 20 are encoded by the universal genetic code. The remaining 2, selenocysteine and pyrrolysine, are incorporated into proteins by unique synthetic mechanisms.

Name/Formula M.W. pI CAS No. Structure
Alanine (Ala/A)
CH3-CH(NH2)-COOH
89.09656-41-7Standard Amino Acids
Arginine (Arg/R)
HN=C(NH2)-NH-(CH2)3-CH(NH2)-COOH
174.211.1574-79-3Amino Acid Peptides
Asparagine (Asn/N)
H2N-CO-CH2-CH(NH2)-COOH
132.125.415794-13-8Asparagine
Aspartic acid (Asp/D)
HOOC-CH2-CH(NH2)-COOH
133.12.7756-84-8Aspartic acid
Cysteine (Cys/C)
HS-CH2-CH(NH2)-COOH
121.155.0252-90-4Cysteine
Glutamine (Gln/Q)
H2N-CO-(CH2)2-CH(NH2)-COOH
146.155.6556-85-9Glutamine
Glutamic acid (Glu/E)
HOOC-(CH2)2-CH(NH2)-COOH
147.133.2256-86-0Glutamic acid
Glycine (Gly/G)
NH2-CH2-COOH
75.075.9756-40-6Glycine
Histidine (His/H)
N=C-NH-C=C-CH2-CH(NH2)-COOH
155.167.4771-00-1Histidine
Isoleucine (Ile/I)
CH3-CH2-CH(CH3)-CH(NH2)-COOH
131.175.9473-32-5Isoleucine
Leucine (Leu/L)
(CH3)2-CH-CH2-CH(NH2)-COOH
131.175.9861-90-5Leucine
Lysine (Lys/K)
H2N-(CH2)4-CH(NH2)-COOH
146.199.5939665-12-8Lysine
Methionine (Met/ M)
CH3-S-(CH2)2-CH(NH2)-COOH
149.215.7463-68-3Methionine
Phenylalanine (Phe/F)
Ph-CH2-CH(NH2)-COOH
165.195.4863-91-2Phenylalanine
Proline (Pro/P)
NH-(CH2)3-CH-COOH
115.136.3147-85-3Proline
Serine (Ser/S)
HO-CH2-CH(NH2)-COOH
105.095.6856-45-1Serine
Threonine (Thr/T)
CH3-CH(OH)-CH(NH2)-COOH
119.125.6472-19-5Threonine
Tryptophan (Trp/W)
Ph-NH-CH-C-CH2-CH(NH2)-COOH
204.235.8973-22-3Tryptophan
Tyrosine (Tyr/Y)
HO-p-Ph-CH2-CH(NH2)-COOH
181.195.6660-18-4Tyrosine
Valine (Val/V)
CH3-CH(CH2)-CH(NH2)-COOH
117.155.9672-18-4Valine