Table 2. Determination of the kinetics parameters of hST6GalNAc III and VI toward MSGG.

Various acceptor substrates were incubated in the standard assay mixture using the membrane fraction of cells transfected with hST6GalNAc III and VI as enzyme sources. Each substrate was used at the concentration of 0.1 mM for glycolipids and 0.4 mg/ml for glycoproteins

		Relative rate (%)*
Acceptor	Structure	III	VI
Fetuin	NeuAcα2,3Galβ1,3GalNAc-Ser/Thr	87	63
	NeuAcα2,3Galβ1,3(NeuAcα2,6)GalNAc-Ser/Thr
	NeuAcα2,6(3)Galβ1,4GlcNAc-R†
Asialo-fetuin		3.2	2.8
BSM	GlcNAcβ1,3(NeuAcα2,6)GalNAc-Ser/Thr	0	0
	NeuAcα2,6GalNAc-Ser/Thr
Asialo-BSM		0	0
GA2	GalNAcβ1,4Galβ1,4Glcβ1-Cer	0	0
GA1	Galβ1,3GalNAcβ1,4Galβ1,4Glcβ1-Cer	0	0
GM1b	NeuAcα2,3Galβ1,3GalNAcβ1,4Galβ1,4Glcβ1-Cer	100	100
GM2	GalNAcβ1,4(NeuAcα2,3)Galβ1,4Glcβ1-Cer	0	0
GM1	Galβ1,3GalNAcβ1,4(NeuAcα2,3)Galβ1,4Glcβ1-Cer	0	0
GD1a	NeuAcα2,3Galβ1,3GalNAcβ1,4(NeuAcα2,3)Galβ1,4Glcβ1-Cer	3.8	7.8
GD3	NeuAcα2,8NeuAcα2,3Galβ1,4Glcβ1-Cer	0	0
GT1b	Gaβ1,3GalNAcβ1,4(NeuAcα2,8NeuAcα2,3)Galβ1,4Glcβ1-Cer	2.4	8.7
Gb3	Galβ1,4Galβ1,4Glcβ1-Cer	0	0
Gb4	GalNAcβ1,3Galβ1,4Galβ1,4Glcβ1-Cer	0	0
Gb5	Galβ1,3GalNAcβ1,3Galβ1,4Galβ1,4Glcβ1-Cer	0	0
MSGG	NeuAcα2,3Galβ1,3GalNAcβ1,3Galβ1,4Galβ1,4Glcβ1-Cer	29	46
DSGG	NeuAcα2,3Galβ1,3GalNAcβ1,3(NeuAcα2,6)Galβ1,4Galβ1,4Glcβ1-Cer	0	0
Lc4	Galβ1,3GlcNAcβ1,3Galβ1,4Glcβ1-Cer	0	0
Sialyl Lc4	NeuAcα2,3Galβ1,3GlcNAcβ1,3Galβ1,4Glcβ1-Cer‡	6	33
Sialyl nLc4	NeuAcα2,3Galβ1,4GlcNAcβ1,3Galβ1,4Glcβ1-Cer‡	0	0
Sialyl Lea	NeuAcα2,3Galβ1,3(Fucα1,4)GlcNAcβ1,3Galβ1,4Glcβ1-Cer	0	0

*Relative rates are calculated as a percentage of the incorporated NeuAc relative to that for GM1b.

†R represents the remainder of the N-linked oligosaccharide chain.

‡Ceramide mimic -CH2(C14H29)2 was chemically bonded to the oligosaccharides instead of ceramide.