Table IV.
Enzyme activity and substrate specificity of ST6Gal-I mutants.
| Oligosaccharide acceptors | Structure | Native | 139C/S | 139C/A | 181C/S | 350C/S | 350C/A |
|---|---|---|---|---|---|---|---|
| Type II | Gal β-1,4GlcNAc | 100a | 94 | 98 | ND | ND | ND |
| Type I | Gal β-1,3GlcNAc | 2 | 1 | 1 | ND | ND | ND |
| Type III | Gal β-1,3GalNAc | 10 | 11 | 9 | ND | ND | ND |
| Lactose | Gal β-1,4Glc | 14 | 11 | 16 | ND | ND | ND |
| Lacto-N-tetraose | Gal β-1,3GlcNAc β-1,3 Gal β-1,4Glc | 35 | 42 | 25 | ND | ND | ND |
| Lacto-N-neotetraose | Gal β-1,4GlcNAc β-1,3 Gal β-1,4Glc | 108 | 102 | 95 | ND | ND | ND |
Each mutant's level of activity in relation to oligosaccharide is shown in proportion to that of the native enzyme for Type II oligosaccharide (Gal β-1,4GlcNAc), which represents 100.
a45.2 pmol/h/ml medium.
ND, not detected.