Biology Reference
In-Depth Information
Table 1. Examples of Post-translational and Chemical Modifications Observed in
Peptides/Proteins
Monoisotopic
Average
Modification
Mass
Mass
Chemical Species + /
Acetylation
+42.0106
+42.0373
+COCH 3
Formylation
+27.9949
+28.0104
+CHO
Methylation
+14.0157
+14.0269
+CH 3
Phoshorylation
+79.9663
+79.9799
+HPO 3
Citrullination
+0.9840
+0.9847
(Arg)-CH 4 N 3 → CH 3 N 2 O
Palmitoylation
+238.2297
+238.4136
+C 16 H 31 O 1 (palmitic acid
moiety) and −H (from
modified amino acid)
Sulfation
+79.9568
+80.0642
+SO 3
O-GlcNAc
+203.0794
+203.1950
+C 8 H 13 O 5 N
Oxidation of Met
+15.9949
+15.9994
+O
Homoserine formed
−29.9928
−30.0935
C 5 H 9 NOS (Met)
from Met by CNBr
→ C 4 H 7 NO 2 (homoSer)
treatment
Pyroglutamic acid
−17.0265
−17.0306
−NH 3
formed from Gln
Disulfide bond formation
−2.0156
−2.0159
−H 2
Deamidation of Asn
+0.9840
+0.9847
C 4 H 6 N 2 O 2 (Asn)
→ C 4 H 5 NO 3
(isoaspartic acid)
Cholesterol
+368.3443
+368.6400
Cholesterol glycine ester
http://www.expasy.ch/tools/findmod/findmod_masses.html
http://www.abrf.org/index.cfm/dm.home
abnormal physiology. This is an excellent approach for obtaining global
difference maps without previous knowledge of what exact biomolecular
species is of interest. More information on this development was reviewed
recently (McDonnell, Heeren, 2007).
MS in structural biology
MS has also become an important tool in structural biology. Because
of the extension in mass range for tandem MS and a phenomenon known
 
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