Materials
Dextran substrate with Mw of 40 kDa was obtained from Sinopharm Co
Standard, China. The Bradford reagent and enzyme of dextranase (EC
3.2.1.11, dry powder from Penilisilium. Sp.) was obtained from
Sigma-Aldrich Co. Ltd. The polyether sulfone UF membrane with MWCO of 20
kDa (PES20) was purchased from AMFOR INC, USA. Milli-Q water was used
for dissolving enzyme and substrate in the experiment.