Table 2.

The K_i values of thiodisaccharides with various β-galactosidases.

Thiodisaccharides	BgaX	BgaC	Ki [μM][a] LacA	hLyBga	LacZ
Gal-β-S-1,3-Glc-pNP (9)	700	n.i.[b]	n.i.[b]	8	9
Gal-β-S-1,3-Gal-pNP (12)	1200	n.i.[b]	n.i.[b]	350	51
Gal-β-S-1,4-Glc-pNP (13)	1300	n.i.[b]	n.i.[b]	1700	150
Gal-β-S-1,3-GlcNAc-pNP (10)	n.i.[b]	n.i.[b]	n.i.[b]	2600	n.i.[b]
Gal-β-S-1,4-GlcNAc-pNP (11)	n.i.[b]	n.i.[b]	n.i.[b]	2500	n.i.[b]

^[a]Each K_i value was determined by using substrate concentrations that ranged from 0.5 × K_m to 2 × K_m for the corresponding enzymes.

^[b]Inhibition was not observed at a 2 mM concentration of thiodisaccharide.