| Ala | GPI-anchor amidated alanine | 53.02655 |
| Ala | N,N-dimethylalanine | 99.068415 |
| Ala | N,N,N-trimethylalanine | 113.084065 |
| Ala | Alanine amide | 70.053099 |
| Ala | Pentaglycyl murein peptidoglycan amidated alanine | 51.0109 |
| Ala | N-acetylalanine | 113.04768 |
| Ala | N-methylalanine | 85.052765 |
| Cys | Cysteine persulfide | 134.981257 |
| Cys | 3-oxoalanine Cys | 85.01638 |
| Cys | S-nitrosocysteine | 131.99935 |
| Cys | Cysteine sulfenic acid -SOH | 119.004101 |
| Cys | N-pyruvate 2-iminyl-cysteine | 173.014665 |
| Cys | N-palmitoyl cysteine | 341.238852 |
| Cys | S-methylcysteine | 117.024836 |
| Cys | S-geranylgeranyl cysteine | 375.259587 |
| Cys | S-palmitoyl cysteine | 341.238852 |
| Cys | S-farnesyl cysteine | 307.196987 |
| Cys | Cysteine sulfinic acid -SO2H | 134.999015 |
| Cys | S-diacylglycerol cysteine | 679.520947 |
| Cys | S-selanylcysteine | 182.925708 |
| Cys | S-archaeol cysteine | 737.671968 |
| Cys | S-8alpha-FAD cysteine | 886.15067 |
| Cys | Pyruvic acid Cys | 70.005481 |
| Cys | Cysteine amide | 102.02517 |
| Cys | Cysteine methyl disulfide | 148.996907 |
| Cys | Cysteine methyl ester | 117.024836 |
| Cys | N-acetylcysteine | 145.019751 |
| Cys | S-stearoyl cysteine | 369.270152 |
| Cys | S-12-hydroxyfarnesyl cysteine | 323.191901 |
| Cys | S-4a-FMN cysteine | 559.113801 |
| Cys | ADP-ribosylcysteine | 644.070295 |
| Cys | Phosphocysteine | 182.975516 |
| Cys | S-6-FMN cysteine | 559.113801 |
| Cys | Farmesylation | 307.196986 |
| Cys | Glutathionylation | 408.07727 |
| Cys | S-Nitrosylation | 131.999356 |
| Cys | Hex-Glycosylation | 265.062015 |
| Cys | Carboxymethylation | 161.0146499 |
| Cys | Carbamidomethylation | 160.0306469 |
| Cys | Pyridylethylation | 208.0664215 |
| Asp | Cis-14-hydroxy-10,13-dioxo-7-heptadecenoic acid aspartate ester | 409.210054 |
| Asp | Aspartic acid 1-amide | 114.042929 |
| Asp | Aspartyl aldehyde | 99.03203 |
| Asp | N-acetylaspartate | 157.03751 |
| Asp | 4-aspartylphosphate | 194.993275 |
| Asp | 3-hydroxyaspartate | 131.02186 |
| Asp | 3-methylthioaspartic acid | 161.014666 |
| Glu | Glutamic acid 1-amide | 128.058579 |
| Glu | Glutamate methyl ester Glu | 143.058245 |
| Glu | Pyrrolidone carboxylic acid Glu | 111.03203 |
| Glu | 4-carboxyglutamate | 173.032424 |
| Glu | N-acetylglutamate | 171.05316 |
| Phe | Phenylalanine amide | 146.084401 |
| Phe | 3-phenyllactic acid | 148.052433 |
| Phe | N-methylphenylalanine | 161.084067 |
| Gly | Cholesterol glycine ester | 425.365766 |
| Gly | N-formylglycine | 85.01638 |
| Gly | 1-thioglycine | 72.998621 |
| Gly | Phosphatidylethanolamine amidated glycine | 756.541755 |
| Gly | N-acetylglycine | 99.03203 |
| Gly | Glycine amide | 56.037449 |
| Gly | N-palmitoyl glycine | 295.251131 |
| Gly | N-myristoyl glycine | 267.21983 |
| His | Pros-8alpha-FAD histidine | 920.200398 |
| His | Tele-methylhistidine | 151.074564 |
| His | Diphthamide | 280.177352 |
| His | Pros-phosphohistidine | 217.025244 |
| His | Histidine amide | 136.074898 |
| His | Pros-methylhistidine | 151.074564 |
| His | Phosphohistidine | 217.025244 |
| His | Tele-8alpha-FMN histidine | 591.147879 |
| His | Methylhistidine | 151.074564 |
| His | Tele-8alpha-FAD histidine | 920.200398 |
| His | Bromohistidine | 214.969427 |
| His | Glucose | 299.111743 |
| His | ADP-Ribosylation | 678.119914 |
| Ile | N-methylisoleucine | 127.099717 |
| Ile | Isoleucine amide | 112.100051 |
| Ile | N-acetylisoleucine | 155.094632 |
| Lys | Pyrrolysine | 237.147731 |
| Lys | Hypusine | 215.163381 |
| Lys | Lysine amide | 127.110951 |
| Lys | Lysine methyl ester | 142.110617 |
| Lys | 5-hydroxylysine | 144.089882 |
| Lys | N6,N6,N6-trimethyl-5-hydroxylysine | 186.136832 |
| Lys | N6,N6,N6-trimethyllysine | 170.141917 |
| Lys | N6,N6-dimethyllysine | 156.126267 |
| Lys | 4,5-dihydroxylysine | 160.084796 |
| Lys | N6-1-carboxyethyl lysine | 200.116096 |
| Lys | N6-acetyllysine | 170.105532 |
| Lys | N6-carboxylysine | 172.084796 |
| Lys | N6-formyllysine | 156.089882 |
| Lys | Allysine | 127.063333 |
| Lys | N6-palmitoyl lysine | 366.324633 |
| Lys | N6-myristoyl lysine | 338.293332 |
| Lys | N6-methylated lysine | 170.141917 |
| Lys | N6-methyllysine | 142.110617 |
| Lys | Glucose | 290.147796 |
| Lys | Galactose | 290.147796 |
| Leu | N-methylleucine | 127.099717 |
| Leu | Leucine methyl ester | 127.099717 |
| Leu | Leucine amide | 112.100051 |
| Met | N-acetylmethionine | 173.051052 |
| Met | N-methylmethionine | 145.056137 |
| Met | Methionine sulfone | 163.030316 |
| Met | Methionine amide | 130.056471 |
| Met | N-formylmethionine | 159.035402 |
| Asn | 3-hydroxyasparagine | 130.037844 |
| Asn | Deamidated asparagine | 115.026945 |
| Asn | N4-methylasparagine | 128.058579 |
| Asn | N4,N4-dimethylasparagine | 142.074229 |
| Asn | Asparagine amide | 113.058913 |
| Asn | Aspartyl isopeptide Asn | 115.026945 |
| Asn | ADP-ribosylasparagine | 655.104038 |
| Asn | N-Acetylglucosamine | 317.12231 |
| Asn | GlcNAc-GlcNAc | 502.19112 |
| Asn | GlcNAc-GlcNAc-Man | 664.24395 |
| Asn | GlcNAc-GlcNAc-Man-Man | 826.29678 |
| Asn | GlcNAc-GlcNAc-Man-Man-Man | 988.34961 |
| Asn | Glucose | 276.09576 |
| Asn | Hex-Glycosylation | 276.09576 |
| Pro | Proline amide | 96.06875 |
| Pro | Hydroxyproline | 113.047681 |
| Pro | 4-hydroxyproline | 113.047681 |
| Pro | N,N-dimethylproline | 125.084066 |
| Pro | 3-hydroxyproline | 113.047681 |
| Pro | 3,4-dihydroxyproline | 129.042595 |
| Pro | N-methylproline | 111.068416 |
| Pro | N-acetylproline | 139.063331 |
| Gln | Glutamine amide | 127.074564 |
| Gln | Omega-hydroxyceramide glutamate ester | 888.789442 |
| Gln | Glutamate methyl ester Gln | 143.058246 |
| Gln | 2-methylglutamine | 142.07423 |
| Gln | N5-methylglutamine | 142.07423 |
| Gln | Pyrrolidone carboxylic acid | 111.032031 |
| Gln | Deamidated glutamine | 129.042596 |
| Gln | Glucose | 290.111409 |
| Arg | ADP-ribosylarginine | 697.162224 |
| Arg | 5-methylarginine | 170.116765 |
| Arg | 4-hydroxyarginine | 172.09603 |
| Arg | Symmetric dimethylarginine | 184.132415 |
| Arg | 3,4-dihydroxyarginine | 188.090944 |
| Arg | Arginine amide | 155.117099 |
| Arg | Asymmetric dimethylarginine | 184.132415 |
| Arg | Citrulline | 157.085131 |
| Arg | Phosphoarginine | 236.067445 |
| Arg | N2-acetylarginine | 198.11168 |
| Arg | Omega-N-methylated arginine | 184.132415 |
| Arg | Omega-N-methylarginine | 170.116765 |
| Arg | N5-methylarginine | 170.116765 |
| Ser | O-palmitoyl serine | 325.261696 |
| Ser | Serine amide | 86.048014 |
| Ser | Serine microcin E492 siderophore ester | 918.229071 |
| Ser | Lactic acid | 72.021131 |
| Ser | ADP-ribosylserine | 628.093139 |
| Ser | Phosphoserine | 166.99836 |
| Ser | O-octanoyl serine | 213.136495 |
| Ser | 3-oxoalanine Ser | 85.01638 |
| Ser | O-decanoyl serine | 241.167795 |
| Ser | O-acetylserine | 129.042595 |
| Ser | O-sn-1-glycerophosphorylserine | 241.03514 |
| Ser | FMN phosphoryl serine | 525.12608 |
| Ser | D-alanine Ser | 71.037115 |
| Ser | Sulfoserine | 166.988845 |
| Ser | Pyruvic acid Ser | 70.005481 |
| Ser | N-acetylserine | 129.042595 |
| Ser | 2,3-didehydroalanine Ser | 69.021465 |
| Ser | N-Acetylgalactosamine | 274.11649 |
| Ser | Beta-D-Gal1:3Beta-D-GalNAc | 452.164243 |
| Ser | Alpha-0-SilicAcid2:3Beta-D-Gal1:3 Beta-D-GalNAc | 743.259653 |
| Ser | Alpha-0-SilicAcid2:3Beta-D-Gal1:3Beta-D-GalNAc<-Alpha-0-SilicAcid2:6 | 1050.349986 |
| Ser | Fucose | 233.08994 |
| Ser | Glucose | 249.084859 |
| Ser | Xylose | 221.08994 |
| Ser | Hex-Glycosylation | 249.084859 |
| Thr | Threonine amide | 100.063665 |
| Thr | N-acetylthreonine | 143.058246 |
| Thr | 2,3-didehydrobutyrine | 83.037116 |
| Thr | Sulfothreonine | 181.004496 |
| Thr | 2-oxobutanoic acid | 84.021132 |
| Thr | O-acetylthreonine | 143.058246 |
| Thr | O-decanoyl threonine | 255.183446 |
| Thr | O-octanoyl threonine | 227.152146 |
| Thr | O-palmitoyl threonine | 339.277347 |
| Thr | Phosphothreonine | 181.014011 |
| Thr | FMN phosphoryl threonine | 539.141731 |
| Thr | N-Acetylgalactosamine | 304.127064 |
| Thr | Beta-D-Gal1:3Beta-D-GalNAc | 466.179894 |
| Thr | Alpha-0-SilicAcid2:3Beta-D-Gal1:3 Beta-D-GalNAc | 757.275304 |
| Thr | Alpha-0-SilicAcid2:3Beta-D-Gal1:3Beta-D-GalNAc<-Alpha-0-SilicAcid2:6 | 1064.35947 |
| Thr | Glucose | 263.10051 |
| Thr | Fucose | 247.105591 |
| Thr | Hex-Glycosylation | 263.10051 |
| Val | N-pyruvate 2-iminyl-valine | 169.073896 |
| Val | D-4-hydroxyvaline | 115.063332 |
| Val | N-acetylvaline | 141.078982 |
| Val | Valine amide | 98.084401 |
| Val | Glucose | 261.121246 |
| Trp | 3'-geranyl-2',N2-cyclotryptophan | 322.204517 |
| Trp | 3-hydroxytryptophan | 202.074231 |
| Trp | 6'-bromotryptophan | 263.989829 |
| Trp | 6'-chlorotryptophan | 220.040344 |
| Trp | N2-succinyltryptophan | 286.09536 |
| Trp | Tryptophan amide | 185.0953 |
| Trp | Tryptophylquinone | 216.053495 |
| Trp | N-Linked Manose | 348.13215 |
| Trp | C-Linked Manose | 348.13215 |
| Trp | Hex-Glycosylation | 348.13215 |
| Tyr | Z-2,3-didehydrotyrosine | 161.047681 |
| Tyr | Thyroxine | 758.676118 |
| Tyr | Triiodothyronine | 632.779475 |
| Tyr | Tyrosine amide | 162.079315 |
| Tyr | Sulfotyrosine | 243.020146 |
| Tyr | 2,3-didehydrotyrosine | 161.047681 |
| Tyr | E-2,3-didehydrotyrosine | 161.047681 |
| Tyr | 2',4',5'-topaquinone | 193.03751 |
| Tyr | 3',4'-dihydroxyphenylalanine | 179.058246 |
| Tyr | Phosphotyrosine | 243.029661 |
| Tyr | O-8alpha-FAD tyrosine | 946.204815 |
| Tyr | N-methyltyrosine | 177.078981 |
| Tyr | Nitrated tyrosine | 208.048409 |
| Tyr | N-acetyltyrosine | 205.073896 |
| Tyr | Glucose | 325.11616 |
| Tyr | Hex-Glycosylation | 325.11616 |