TABLE 1.

Ratio of NRE disaccharides to internal disaccharides

Disaccharidea	NRE massb (m/z)	Internal mass (m/z)	Intensity ratio (NRE/internal) (%)
			Control (%)	4F-GlcNAc (Ac3)(%)	6F-GalNAc (Ac3)(%)
HS: UA-GlcNS+1S	591.08	573.07	1.9	10.8	10.8
CS/DS: UA-GalNAc+1S	553.14	535.13	2.0	6.2	6.5

GAGs of SKOV3 cells cultured with 50 µM 6F-GalNAc (Ac₃) or 4F-GlcNAc (Ac₃) were depolymerized by chondroitinase ABC for CS/DS analysis or by a combination of heparinases I, II, and III for HS analysis. Samples were analyzed by LC/MS on an LTQ Orbitrap Discovery system (Thermo Fisher Scientific) equipped with a C-18 RP microbore column. ^a1S indicates that 1 SO₃⁻ group is present. In the case of HS, the most likely structures are UA2S-GlcNS and UA-GlcNS6S. For CS/DS, the most likely structures are UA-GalNAc4S and UA-GalNAc6S.^bThe mass of the NRE disaccharide is +18 amu over the corresponding internal disaccharide, because of the elimination of an H₂O molecule from the internal disaccharide by heparinase.