Mass Values for Peptide Fragment Ions

One Letter Code Amino Acid Three Letter Code Mono Isotopic Integer Residue Mass (Da)

Mass Change (Da)

# of Carbon Atoms Methyl Ester Mass or Phosphate Mono Isotopic Accurate Residue Mass Average Residue Mass
G Glycine Gly 57 0 2   57.02 57.05
A Alanine Ala 71 14 3   71.04 71.08
S Serine Ser 87 16 3 167 Da 87.03 87.08
P Proline Pro 97 10 5   97.05 97.12
V Valine Val 99 2 5   99.07 99.13
T Threonine Thr 101 2 4 181 Da 101.05 101.11
C Cysteine Cys 103 2 3   103.01 103.14
L Leucine Leu 113 10 6   113.08 113.16
I Isoleucine Ile 113   6   113.08 113.16
N Asparagine Asn 114 1 4   114.04 114.1
D Aspartic Acid Asp 115 1 4 129 Da 115.03 115.09
K Lysine Lys 128 13 6   128.09 128.17
Q Glutamine Gln 128   5   128.06 128.13
E Glutamic Acid Glu 129 1 5 143 Da 129.04 129.12
M Methionine Met 131 2 5   131.04 131.19
H Histidine His 137 6 6   137.06 137.14
F Phenylalanine Phe 147 10 9   147.07 147.18
R Arginine Arg 156 9 6   156.1 156.19
Y Tyrosine Tyr 163 7 9 243 Da 163.06 163.18
W Tryptophan Trp 186 23 11   186.08 186.21
 
  Hydrogen H 1       1.008 1.008
Carbon C 12       12 12.011
Nitrogen N 14       14.003 14.007
Oxygen O 16       15.995 15.999
Sulfur S 32       31.972 32.06
Methyl   15       15.02 15.04
Water   18       18.01 18.02
Acetyl   43       43 43.05