Table 2 Relative activity of purified Gal308 with several nitrophenyl-derived chromogenic substrates and its natural substrate lactose

o-Nitrophenyl-β-D-galactopyranoside (ONPG)

100

p-Nitrophenyl-β-D-galactopyranoside (pNPG)

<1

o-Nitrophenyl-β-D-fucopyranoside

<1

p-Nitrophenyl-β-D-mannoside

3.5±0.3

o-Nitrophenyl-β-D-glucoside

<1

p-Nitrophenyl-β-D-xyloside

5.7±0.2

p-Nitrophenyl-β-D-cellobioside

<1

p-Nitrophenyl-β-D-lactoside

7.8±0.3

p-Nitrophenyl-α-D-galactoside

<1

Lactose

25.7±1.8