A novel β-glucosidase from Aspergillus fumigates releases diosgenin from spirostanosides of Dioscorea zingiberensis C. H. Wright (DZW).
A β-glucosidase effectively releasing diosgenin from spirostanosides of Dioscorea zingiberensis C. H. Wright (DZW), named AfG, was purified from a strain of Aspergillus fumigates. The molecular weight of AfG was 113 kDa. Analysis of protein fragments by ESI-Q-TOF indicated that AfG was a β-glucosidase. The circular dichroism spectrum suggested that the main secondary structure of AfG in Milli-Q water was α-helixes. Atomic force microscopy revealed that it was a globular protein. AfG maintained high activity from pH 3.6 to 5.0 and from 50 to 90°C. With the strong heat stability, AfG retained 55% of its original activity at 65°C for 120 h. AfG utilized muti-3-O-glycosides of various steroidal saponins from DZW as substrate, such as trillin, diosgenin diglucoside, dioscin, deltonin and gracillin, to yield diosgenin, suggesting the possibility of producing diosgenin from total saponins of DZW using a single enzyme.
Department of Environmental Engineering, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing 100871, China.
Jing
J
Lei
Hai
H
Niu
Tianhong
T
Li
Wen
W
Huang
D001230:Aspergillus / Q000201:enzymology*; D002942:Circular Dichroism; D027742:Dioscorea / Q000737:chemistry*; D004144:Diosgenin / Q000378:metabolism*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D017433:Protein Structure, Secondary; D012503:Saponins / Q000378:metabolism; D013150:Spirostans / Q000378:metabolism*; D013696:Temperature; D001617:beta-Glucosidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
D012503:Saponins; D013150:Spirostans; D001617:beta-Glucosidase; D004144:Diosgenin