Table 1 A list of the PG modifications searched for, and the strategy used to validate them
Modification | Description | Retention time | Mass change | Signature ion m/z ([M+H]+) | Relative abundance | Present | |
|---|---|---|---|---|---|---|---|
Glycan modifications | 1) Similar % of modified monomers for all monomers 2) Relative abundance of modified monomers should be similar to the relative abundance of unmodified monomers | ||||||
AnhydroMurNAc | (Anh) | 1,6-anhydroMurNAc | Increased | −20.026 | 258.096 (AnhMurNAc) | YES | |
Deacetylation | (DeAc) | Loss of acetyl group | Decreased | −42.010 | 162.077 (GlcN); 236.113 (MurNred) | NO | |
O-acetylation | (Ac) | Gain of acetyl group | Increased | +42.010 | 246.098 (GlcNAc+Ac) | NO | |
320.134 (MurNAcred+Ac) | |||||||
Peptide modifications | |||||||
Amidation | (Am) | Glu or mDap amidation | Decreased | −0.984 | 172.109 (mDAPNH2); 129.066 (Gln) | NO | |
Hydrolysis products | |||||||
Loss of g | Glucosaminidase | Decreased | −203.079 | 278.124 (MurNAcred) | NO | ||
product | 206.087 (MurNAcred -Lactyl) | ||||||
Extra gm | Partial muramidase digestion | Increased | +478.180 | 276.108 (MurNAc) | NO | ||
