TY - JOUR
T1 - Lactose hydrolysis by β-galactosidase in aqueous two-phase systems
AU - Chen, Jyh Ping
AU - Wang, Cheng Hsin
PY - 1991
Y1 - 1991
N2 - Lactose hydrolysis was studied in aqueous two-phase systems with β-galactosidases from bacteria (Escherichia coli), yeast (Saccharomyces fragilis), and fungi (Aspergillus oryzae). Salts such as potasium phosphate, ammonium sulfate, and sodium citrate used at concentrations forming phase systems could severely inhibit β-galactosidase activity from yeast and inhibit E. coli enzyme activity to a lesser extent, but had no effect on fungal β-galactosidase activity. Polymers such as polyethylene glycol (PEG) and a modified starch (Reppal PES) could increase the enzyme activity toward hydrolyzing o-nitrophenyl-β-d-galactopyranoside. E. coli β-galactosidase showed a partition coefficient of 127 in a PEG/Reppal PES system to provide an efficient system for carrying out extractive hydrolysis of lactose. A. oryzae β-galactosidase showed a partition coefficient of 0.0042 in a PEG/sodium citrate system. Continuous hydrolysis of lactose in this system with a mixer-settler enzyme reactor could be operated for a period of 84 h with only 10% loss of enzyme activity. Slower reaction rates in two-phase systems than in buffer systems may arise from preferential distributions of both enzyme and inhibitory products into the same phase.
AB - Lactose hydrolysis was studied in aqueous two-phase systems with β-galactosidases from bacteria (Escherichia coli), yeast (Saccharomyces fragilis), and fungi (Aspergillus oryzae). Salts such as potasium phosphate, ammonium sulfate, and sodium citrate used at concentrations forming phase systems could severely inhibit β-galactosidase activity from yeast and inhibit E. coli enzyme activity to a lesser extent, but had no effect on fungal β-galactosidase activity. Polymers such as polyethylene glycol (PEG) and a modified starch (Reppal PES) could increase the enzyme activity toward hydrolyzing o-nitrophenyl-β-d-galactopyranoside. E. coli β-galactosidase showed a partition coefficient of 127 in a PEG/Reppal PES system to provide an efficient system for carrying out extractive hydrolysis of lactose. A. oryzae β-galactosidase showed a partition coefficient of 0.0042 in a PEG/sodium citrate system. Continuous hydrolysis of lactose in this system with a mixer-settler enzyme reactor could be operated for a period of 84 h with only 10% loss of enzyme activity. Slower reaction rates in two-phase systems than in buffer systems may arise from preferential distributions of both enzyme and inhibitory products into the same phase.
UR - http://www.scopus.com/inward/record.url?scp=0026101034&partnerID=8YFLogxK
U2 - 10.1016/0922-338X(91)90104-O
DO - 10.1016/0922-338X(91)90104-O
M3 - 文章
AN - SCOPUS:0026101034
SN - 0922-338X
VL - 71
SP - 168
EP - 175
JO - Journal of Fermentation and Bioengineering
JF - Journal of Fermentation and Bioengineering
IS - 3
ER -