Amino Acid and Codon Table

Table of standard amino acid abbreviations and properties

Amino Acid 3-Letter[94] 1-Letter[94] Side-chain polarity[94] Side-chain charge (pH 7.4)[94] Hydropathy index[95] Absorbance λmax(nm)[96] ε at λmax (x10−3 M−1 cm−1)[96]
Aspartic acid Asp D polar negative −3.5
Glutamic acid Glu E polar negative −3.5
Asparagine Asn N polar neutral −3.5
Cysteine Cys C polar neutral 2.5 250 0.3
Alanine Ala A nonpolar neutral 1.8
Glutamine Gln Q polar neutral −3.5
Glycine Gly G nonpolar neutral −0.4
Isoleucine Ile I nonpolar neutral 4.5
Leucine Leu L nonpolar neutral 3.8
Methionine Met M nonpolar neutral 1.9
Phenylalanine Phe F nonpolar neutral 2.8 257, 206, 188 0.2, 9.3, 60.0
Proline Pro P nonpolar neutral −1.6
Serine Ser S polar neutral −0.8
Threonine Thr T polar neutral −0.7
Tryptophan Trp W nonpolar neutral −0.9 280, 219 5.6, 47.0
Tyrosine Tyr Y polar neutral −1.3 274, 222, 193 1.4, 8.0, 48.0
Valine Val V nonpolar neutral 4.2
Arginine Arg R polar positive −4.5
Lysine Lys K polar positive −3.9
Histidine His H polar positive(10%)

neutral(90%)

−3.2 211 5.9


In addition, there are two additional amino acids that are incorporated by overriding stop codons:

21st and 22nd amino acids 3-Letter 1-Letter
Selenocysteine Sec U
Pyrrolysine Pyl O

In addition to the specific amino acid codes, placeholders are used in cases where chemical or crystallographic analysis of a peptide or protein cannot conclusively determine the identity of a residue.

Ambiguous Amino Acids 3-Letter 1-Letter
Asparagine or aspartic acid Asx B
Glutamine or glutamic acid Glx Z
Leucine or Isoleucine Xle J
Unspecified or unknown amino acid Xaa X

Unk is sometimes used instead of Xaa, but is less standard.

In addition, many non-standard amino acids have a specific code. For example, several peptide drugs, such as Bortezomib and MG132, are artificially synthesized and retain their protecting groups, which have specific codes. Bortezomib is Pyz-Phe-boroLeu, and MG132 is Z-Leu-Leu-Leu-al. To aid in the analysis of protein structure, photocrosslinking amino acid analogues are available. These include photoleucine (pLeu) and photomethionine (pMet).[97]

RNA codon table

nonpolar polar basic acidic (stop codon)
2nd base
U C A G
1st base U UUU (Phe/F) Phenylalanine UCU (Ser/S) Serine UAU (Tyr/Y) Tyrosine UGU (Cys/C) Cysteine
UUC (Phe/F) Phenylalanine UCC (Ser/S) Serine UAC (Tyr/Y) Tyrosine UGC (Cys/C) Cysteine
UUA (Leu/L) Leucine UCA (Ser/S) Serine UAA Stop (Ochre) UGA Stop (Opal)
UUG (Leu/L) Leucine UCG (Ser/S) Serine UAG Stop (Amber) UGG (Trp/W) Tryptophan
C CUU (Leu/L) Leucine CCU (Pro/P) Proline CAU (His/H) Histidine CGU (Arg/R) Arginine
CUC (Leu/L) Leucine CCC (Pro/P) Proline CAC (His/H) Histidine CGC (Arg/R) Arginine
CUA (Leu/L) Leucine CCA (Pro/P) Proline CAA (Gln/Q) Glutamine CGA (Arg/R) Arginine
CUG (Leu/L) Leucine CCG (Pro/P) Proline CAG (Gln/Q) Glutamine CGG (Arg/R) Arginine
A AUU (Ile/I) Isoleucine ACU (Thr/T) Threonine AAU (Asn/N) Asparagine AGU (Ser/S) Serine
AUC (Ile/I) Isoleucine ACC (Thr/T) Threonine AAC (Asn/N) Asparagine AGC (Ser/S) Serine
AUA (Ile/I) Isoleucine ACA (Thr/T) Threonine AAA (Lys/K) Lysine AGA (Arg/R) Arginine
AUG[A] (Met/M) Methionine ACG (Thr/T) Threonine AAG (Lys/K) Lysine AGG (Arg/R) Arginine
G GUU (Val/V) Valine GCU (Ala/A) Alanine GAU (Asp/D) Aspartic acid GGU (Gly/G) Glycine
GUC (Val/V) Valine GCC (Ala/A) Alanine GAC (Asp/D) Aspartic acid GGC (Gly/G) Glycine
GUA (Val/V) Valine GCA (Ala/A) Alanine GAA (Glu/E) Glutamic acid GGA (Gly/G) Glycine
GUG (Val/V) Valine GCG (Ala/A) Alanine GAG (Glu/E) Glutamic acid GGG (Gly/G) Glycine
A The codon AUG both codes for methionine and serves as an initiation site: the first AUG in an mRNA‘s coding region is where translation into protein begins.[30]
Inverse table
Ala/A GCU, GCC, GCA, GCG Leu/L UUA, UUG, CUU, CUC, CUA, CUG
Arg/R CGU, CGC, CGA, CGG, AGA, AGG Lys/K AAA, AAG
Asn/N AAU, AAC Met/M AUG
Asp/D GAU, GAC Phe/F UUU, UUC
Cys/C UGU, UGC Pro/P CCU, CCC, CCA, CCG
Gln/Q CAA, CAG Ser/S UCU, UCC, UCA, UCG, AGU, AGC
Glu/E GAA, GAG Thr/T ACU, ACC, ACA, ACG
Gly/G GGU, GGC, GGA, GGG Trp/W UGG
His/H CAU, CAC Tyr/Y UAU, UAC
Ile/I AUU, AUC, AUA Val/V GUU, GUC, GUA, GUG
START AUG STOP UAA, UGA, UAG

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