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Amino Acid Masses Tables

Amino Acid Table

Masses of Biological Molecules

Monoisotopic amino acid residue masses and immonium ion masses.

The designations of -, +, and ++ roughly indicate which immonium ions are most abundant.
In the case of lysine, the immonium ion usually loses ammonia to give an ion at 84 u.
There are a few other odd-ball amino acid fragments that have been left out of the list, but these are the main ones.

Amino acids     Residue mass Immonium ion
Glycine Gly G 5 7 .02147 30.03438 (-)
Alanine Ala A 71.03712 44.05003 (-)
Serine Ser S 87.03203 60.04494 (+)
Proline Pro P 97.05277 70.06568 {++)
Valine Val V 99.06842 72.08133 (++)
Threonine Thr T 101.04768 74.06059 (+)
Cysteine Cys C 103.00919 76.0221 (-)
Carbamidomethylated     160.03065 133.0436 (+)
Carboxymethylated     161.01466 134.0276 (+)
Acrylamide adduct     174.0643 147.0772 (+)
Isoleucine Ile I 113.08407 86.09698 {++)
Leucine Leu L 113.08407 86.09698 {++)
Asparagine Asn N 114.04293 87.05584 (+)
Aspartic acid Asp D 115.02695 88.03986 (+)
Glutamine Gln Q 128.05858 101.0715 (+)
Lysine Lys K 128.09497 101.1079 (84.08136)
Glutamic acid Glu E 129.0426 102.0555 (+)
Methionine Met M 131.04049 104.0534 (+)
Oxidized methionine     147.0354 120.0483 {+)
Histidine His H 137.05891 110.0718 {++)
Phenylalanine Phe F 147.06842 120.0813 {++)
Arginine Arg R 156.10112 129.114 (-)
Tyrosine Tyr Y 163.06333 136.0762 {++)
Tryptophan Trp W 186.07932 159.0922 (+)

Masses of Biological Molecules

Amino Acid Masses                  
A Ala C3H5ON 71.03711 71.0788   GG 114.04294 AA 142.07422 LA 174.0463
R Arg C6H12ON4 156.10111 156.1875   GA 128.05859 AR 156.10111 LR 259.1103
N Asn C4H6O2N2 114.04293 114.1038   GS 57.02147 AN 114.04293 LN 217.05212
D Asp C4H5O3N 115.02694 115.0886   GP 71.03712 AD 115.02694 LD 218.03613
C Cys C3H5ONS 103.00919 103.1388   GV 87.03203 AC 103,00919 LC 206.01838
E Glu C5H7O3N 129.04259 129.1155   GT 97.05277 AE 129.04259 LE 232.05178
Q Gln C5H8O2N2 128.05858 128.1307   GC 99.06842 AQ 128.05858 LQ 231.06777
G Gly C2H3ON 57.02146 57.0519   GI 101.04768 AG 57.02146 LG 160.03065
H His C6H7ON3 137.05891 137.1411   GL 103.00919 AH 137.05891 LH 240.0681
I lle C6H110N 113.08406 113.1594   GN 113.08407 Al 113.08406 LI 216.09325
L Leu C6H110N 113.08406 113.1594   GD 113.08407 AL 113.08406 LL 216.09325
K Lys C6H12ON2 128.09496 128.1741   GQ 114.04293 AK 128.09496 LK 231.10415
M Met C5H9ONS 131.04049 131.1926   GK 115.02695 AM 131.04049 LM 234.04968
F Phe C9H9ON 147.06841 147.1766   GE 128.05858 AF 147.06841 LF 250.0776
P Pro C5H7ON 97.05276 97.1167   GM 129.0426 AP 97.05276 LP 200.06195
S Ser C3H5O2N 87.03203 87.0782   GH 113,11 AS 87.03203 LS 190.04122
T Thr C4H7O2N 101.04768 101.1051   GF 131.04049 AT 101,04768 LT 204.05687
W Trp C11H10ON2 186.07931 186.2132   GR 137.05891 AW 186.07931 LW 289.0885
Y Tyr C9H9O2N 163.06333 163.176   GY 147.06842 AY 163.06333 LY 266.07252
V Val C5H9ON 99.06841 99.1326   GW 156.10112 AV 99.06841 LV 202.0776


Amino Acid Residues         M+H+ Amino Acids   Low mass ions      
      Monoisotop Average   Average pI   Immoniun others side chain
Glycine Gly G 57.02147 57.052 75 75.07 5.97   30   1
Alanine Ala A 71.03712 71.079   89.1 6   44   14
Serine Ser S 87.03203 87.078   105.09 5.68   60   31
Proline Pro P 97.05277 97.117   115.13 6.3   70   42
Valine Val V 99.06842 99.133   117.15 5.96   72 41, 55, 69 43
Threonine Thr T 101.04768 101.105   119.12 5.6   74   45
Cysteine Cys C 103.00919 103.144   121.16 5.07   76   47
Isoleucine lle l 113.08407 113.16   131.18 6.02   86 44, 72 57
Leucine Leu L 113.08407 113.16   131.18 5.98   86 44, 72 57
Asparagine Asn N 114.04293 114.104   132.12 5.41   87 7 0 58
Aspartic Acid Asp D 115.02695 115.089   133.11 2.77   88 70 59
Glutamine Gln Q 128.05858 128.131   146.15 5.65   101 56, 84, 129 72
Lysine Lys K 128.09497 128.174   146.19 9.74   101 84, 112, 129 72
Glutamic Acid Glu E 129.0426 129.116   147.13 3.22   102 84, 91 73
Hydroxyproline Hyp O 113.11 113.11   131.13          
Methionine Met M 131.04049 131.198   149.21 5.74   104   75
Histidine His H 137.05891 137.142   155.16 7.59   110   81
Phenylalanine Phe F 147.06842 147.177   165.19 5.48   120 91 91
Arginine Arg R 156.10112 156.188   174.2 10.76   129 70, 87, 100, 112 100
Tyrosine Tyr Y 163.06333 163.17   181.19 5.66   136 91, 107 107
Tryptophan Try W 186.07932 186.213   204.23 5.89   159 77, 117, 130, 132 130
Carbamidomethyl Cys CaC CaC             132   103
Carboxymethyl Cys CmC CmC             133   104

Masses of Biological Molecules

This table lists dipeptide masses (sum of residue masses + 1Da).
The values are useful for assigning internal fragment-ions and the b2 ion in tandem mass spectra

  Leu/     Gin/       Met-     Cys-   Cys-  
  Gly Ala Ser Pro Val Thr Cys lie Asn Asp Lys Glu Met His ox Phe Arg cm Tyr am Trp
  G A S P V T C L/I N D Q/K E M H M-ox F R C-cm Y C-am W
    57 71 87 97 99 101 103 113 114 115 128 129 131 137 147 147 156 161 163 174 186
Gly G 57 115                                        
Ala A 71 129 143                                      
Ser S 87 145 159 175                                    
Pro P 97 155 169 185 195                                  
Val V 99 157 171 187 197 199                                
Thr T 101 159 173 189 199 201 203                              
Cys C 103 161 175 191 201 203 205 207                            
Leu/Ile L/I 113 171 185 201 211 213 215 217 227                          
Asn N 114 172 186 202 212 214 216 218 228 229                        
Asp D 115 173 187 203 213 215 217 219 229 230 231                      
Gln/Lys Q/K 128 186 200 216 226 228 230 232 242 243 244 257                    
Glu E 129 187 201 217 227 229 231 233 243 244 245 258 259                  
Met M 131 189 203 219 229 231 233 235 245 246 247 260 261 263                
His H 137 195 209 225 235 237 239 241 251 252 253 266 267 269 275              
Met-ox M-ox 147 205 219 235 245 247 249 251 261 262 263 276 277 279 285 295            
Phe F 147 205 219 235 245 247 249 251 261 262 263 276 277 279 285 295 295          
Arg R 156 214 228 244 254 256 258 260 270 271 272 285 286 288 294 304 304 313        
cys-cm C-cm 161 219 233 249 259 261 263 265 275 276 277 290 291 293 299 309 309 318 323      
Tyr Y 163 221 235 251 261 263 265 267 277 278 279 292 293 295 301 311 311 320 325 327    
cys-am C-am 174 232 246 262 272 274 276 278 288 289 290 303 304 306 312 322 322 331 336 338 349  
Trp W 186 244 258 274 284 286 288 290 300 301 302 315 316 318 324 334 334 343 348 350 361 373

Note: C-cm; carboxy-methyl Cys | C-am; acrylamide-modified Cys | M-ox; oxidized Met
• Residues DOWN the left indicate the EXPECTED residues
• Residues ACROSS the top indicate the MUTANT residues,

    G A S P V T C L/I N D Q/K E M H F R Y W
    57 71 87 97 99 101 103 113 114 115 128 129 131 137 147 156 163 186
G 57   14 30 40 42 44 46 56 57 58 71 72 74 80 90 99 106 129
A 71 -14   16 26 28 30 32 42 43 44 57 58 60 66 76 85 92 115
S 87 -30 -16   10 12 14 16 26 27 28 41 42 44 50 60 69 76 99
P 97 -40 -26 -10   2 4 6 16 17 18 31 32 34 40 50 59 66 89
V 99 -42 -28 -12 -2   2 4 14 15 16 29 30 32 38 48 57 64 87
T 101 -44 -30 -14 -4 -2   2 12 13 14 27 28 30 36 46 55 62 85
C 103 -46 -32 -16 -6 -4 -2   10 11 12 25 26 28 34 44 53 60 83
L/I 113 -56 -42 -26 -16 -14 -12 -10   1 2 15 16 18 24 34 43 50 73
N 114 -57 -43 -27 -17 -15 -13 -11 -1   1 14 15 17 23 33 42 49 72
D 115 -58 -44 -28 -18 -16 -14 -12 -2 -1   13 14 16 22 32 41 48 71
Q/K 128 -71 -57 -41 -31 -29 -27 -25 -15 -14 -13   1 3 9 19 28 35 58
E 129 -72 -58 -42 -32 -30 -28 -26 -16 -15 -14 -1   2 8 18 27 34 57
M 131 -74 -60 -44 -34 -32 -30 -28 -18 -17 -16 -3 -2   6 16 25 32 55
H 137 -80 -66 -50 -40 -38 -36 -34 -24 -23 -22 -9 -8 -6   10 19 26 49
F 147 -90 -76 -60 -50 -48 -46 -44 -34 -33 -32 -19 -18 -16 -10   9 16 39
R 156 -99 -85 -69 -59 -57 -55 -53 -43 -42 -41 -28 -27 -25 -19 -9   7 30
Y 163 -106 -92 -76 -66 -64 -62 -60 -50 -49 -48 -35 -34 -32 -26 -16 -7   23
W 186 -129 -115 -99 -89 -87 -85 -83 -73 -72 -71 -58 -57 -55 -49 -39 -30 -23  

Masses of Biological Molecules

This table lists the delta masses between various amino acids and can be used to help explain how an observed mass change
could represent an AA mutation.
• Residues DOWN the left indicate the EXPECTED residues.
• Residues ACROSS the top indicate the MUTANT residues.

    G A S P V T C L/I N D Q/K E M H F R Y W
    57 71 87 97 99 101 103 113 114 115 128 129 131 137 147 156 163 186
G 57   14 30 40 42 44 46 56 57 58 71 72 74 80 90 99 106 129
A 71 -14   16 26 28 30 32 42 43 44 57 58 60 66 76 85 92 115
S 87 -30 -16   10 12 14 16 26 27 28 41 42 44 50 60 69 76 99
P 97 -40 -26 -10   2 4 6 16 17 18 31 32 34 40 50 59 66 89
V 99 -42 -28 -12 -2   2 4 14 15 16 29 30 32 38 48 57 64 87
T 101 -44 -30 -14 -4 -2   2 12 13 14 27 28 30 36 46 55 62 85
C 103 -46 -32 -16 -6 -4 -2   10 11 12 25 26 28 34 44 53 60 83
L/I 113 -56 -42 -26 -16 -14 -12 -10   1 2 15 16 18 24 34 43 50 73
N 114 -57 -43 -27 -17 -15 -13 -11 -1   1 14 15 17 23 33 42 49 72
D 115 -58 -44 -28 -18 -16 -14 -12 -2 -1   13 14 16 22 32 41 48 71
Q/K 128 -71 -57 -41 -31 -29 -27 -25 -15 -14 -13   1 3 9 19 28 35 58
E 129 -72 -58 -42 -32 -30 -28 -26 -16 -15 -14 -1   2 8 18 27 34 57
M 131 -74 -60 -44 -34 -32 -30 -28 -18 -17 -16 -3 -2   6 16 25 32 55
H 137 -80 -66 -50 -40 -38 -36 -34 -24 -23 -22 -9 -8 -6   10 19 26 49
F 147 -90 -76 -60 -50 -48 -46 -44 -34 -33 -32 -19 -18 -16 -10   9 16 39
R 156 -99 -85 -69 -59 -57 -55 -53 -43 -42 -41 -28 -27 -25 -19 -9   7 30
Y 163 -106 -92 -76 -66 -64 -62 -60 -50 -49 -48 -35 -34 -32 -26 -16 -7   23
W 186 -129 -115 -99 -89 -87 -85 -83 -73 -72 -71 -58 -57 -55 -49 -39 -30 -23  

All values are (column-row). The mass difference observed is consistent with a ROW to COLUMN mutation.