Synthetic protecting groups
Protecting group Mass Change
Methyl14.027 (Me)
Formyl28.104 (CHO)
Ethyl28.054 (Et)
Acetyl42.037 (Ac)
t-Butyl56.108 (t-Bu)
Anisyl90.126
Benzyl90.126 (Bzl)
Trifluroacetyl96.009 (Tfa)
N-hydroxysuccinimide97.073 (ONSu, OSu)
t-Butyloxycarbonyl100.117 (Boc)
Benzoyl104.108 (Bz)
4-Methylbenzyl104.152 (Meb)
Thioanizyl106.191
Thiocresyl106.191
Benzyloxymethyl120.151 (Bom)
4-Nitrophenyl121.095 (ONp)
Benzyloxycarbonyl134.134 (Z)
2-Nitrobenzoyl149.106 (NBz)
2-Nitrophenylsulphenyl153.161 (Nps)
4-Toluenesulphonyl154.189 (Tosyl,Tos)
Pentafluorophenyl166.050 (Pfp)
Diphenylmethyl (Dpm)166.222 (Dpm)
2-Chlorobenzyloxycarbonyl168.579 (Cl-Z)
2,4,5-trichlorophenyl179.432
2-bromobenzyloxycarbonyl213.031 (Br-Z)
9-Fluorenylmethyloxycarbonyl222.243 (Fmoc)
Tripheylmethyl242.320 (Trityl, Trt)
2,2,5,7,8-pentamethyl-chroman-6-sulphonyl266.361 (Pmc)

The masses of commonly occuring protecting groups used in solid phase synthesis. The masses quoted are the average mass change in a peptide when one of these groups is present.


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