Beta-glucosidase isolated from soybean okara shows specificity toward glucosyl isoflavones.
A novel beta-glucosidase was isolated from soybean okara in this study. Along with the beta-glucosidase, a considerable basic 7S globulin of soybean was obtained in the initial extraction products. The protein samples pretreated with 130 mM dithiothreitol before the step of CM-Sepharose chromatography could greatly enhance the separation of the targeted beta-glucosidase from the impurities. The purified beta-glucosidase was found to be a monomer estimated to be 75 kDa by SDS-PAGE. The optimal temperature and pH for this beta-glucosidase were 45 degrees C and 4.5, respectively. The activity of this purified beta-glucosidase was completely inhibited by 1 mM Hg(2+) or 10 mM Al(3+) ion, and glucose and mannose also affected the activity. This beta-glucosidase possessed strict specificity toward glucosyl isoflavones but not malonylglucosidic conjugates of isoflavones of soybean. The N-terminal amino acid sequence of the beta-glucosidase was EYLKYKDPKA-, which highly matched that of glycosidases in maize (Zea mays) and wheat (Triticum asetivum).
Chiou
Tai-Ying
TY
Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Lin
Yi-Hsuan
YH
Su
Nan-Wei
NW
Lee
Min-Hsiung
MH
D004795:Enzyme Stability; D007529:Isoflavones / Q000737:chemistry*; D007700:Kinetics; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D013025:Glycine max / Q000737:chemistry / Q000201:enzymology*; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000737:chemistry* / Q000302:isolation & purification
D007529:Isoflavones; D010940:Plant Proteins; D001617:beta-Glucosidase