Table I.
a The mass shifts of isotopomers represent the numbers of incorporated 13C2-GlcN in each glycan.
b The incorporations of one 13C2-GlcN in these glycans lead to the 2 mass shift for one 13C2-GlcN residue. since the glycans were detected as single charged ions.
c Ratio of unlabeled ions to total isotopomers were calculated by the procedure described in “Experimental Procedures”.