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Sun Y.,Northeast Agricultural University | Sun Y.,Chinese Education Ministrys and Provincial Key Laboratory of Soybean Biology | Zhang Y.,Northeast Agricultural University | Zhang Y.,Chinese Education Ministrys and Provincial Key Laboratory of Soybean Biology | And 3 more authors.
Journal of Medicinal Plants Research | Year: 2010

We had studied the purification and characterization of β-glucosidase from Lentinula edodes, and its activity of hydrolyzing genistin and daidzin. The beta-glucosidase was extracted from an edible mushrooms L. edodes fruiting body and concentrated 26.5-fold by (NH4) 2SO4 precipitation, followed by CM-Sephadex C-50 and Sephacryl S-300 HR chromatography. The purified enzyme showed a single 66 kd band on SDS-PAGE. The optimal enzyme activity occurred at 60°C and pH 4.0 in hydrolysis of genistin, daidzin and p-NPG. The enzyme activity was completely inhibited by 5 mM Ag +, Cu 2+ or Al 3+, respectively. The enzyme had apparent the Km values of 0.347, 0.070 and 0.150 mM and Vmax values of 84878, 225 and 639 nkat•mg of protein-1 for the hydrolysis of p-NPG, genistin and daidzin, respectively, at 60°C and pH 5.0. All tested organic solvents inhibited the β-glucosidase activity on hydrolysis of genistin and daidzin. The hydrolysis efficiency of daidzin and genistin could come up to 97 and 92%, respectively with enough enzyme addition. These experiments demonstrate that β-glucosidase from L. edodes has high activities for hydrolysis of daidzin and genistin, and are likely to be used in the transformation of isoflavone glucosides into aglucones. © 2010 Academic Journals.

Zhang B.,Northeast Agricultural University | Zhang B.,Chinese Education Ministrys and Provincial Key Laboratory of Soybean Biology | Chi Y.J.,Northeast Agricultural University | Chi Y.J.,Chinese Education Ministrys and Provincial Key Laboratory of Soybean Biology | And 2 more authors.
European Food Research and Technology | Year: 2014

Soy β-conglycinin (7S) was grafted with maltodextrin (MD) by combined ultrasound treatment and wet heating Maillard reaction in this work. The physicochemical and emulsifying properties of 7S-MDH (classical wet heating) and 7S-MDUH (ultrasound-assisted wet heating grafting) have been investigated. Ultrasound treatment could speed up the conjugation process and obtain a protein-polysaccharide conjugate that exhibits superior functionality compared with the one obtained simply by wet heat treatment. The degree of grafting of 32.73 % was obtained in 30 min by ultrasound-assisted wet heating, whereas classical wet heating required 60 min. SDS-PAGE analysis indicated that 7S globulin had become complex with MD to form conjugates of higher molecular weight. Reduction in the contents of lysine and arginine during the graft reaction indicated that these two amino acid residues had the covalent linkage between 7S and MD. The results of secondary structure showed that grafted 7S had decreased α-helix level and increased β-sheet and unordered coil levels. In addition, ultrasound-assisted treatment significantly changes in surface hydrophobicity (H 0), emulsifying activity index and emulsifying stability index of 7S (p < 0.05). Moreover, the emulsions of 7S-MDUH were stable under unfavorable conditions, such as extreme pH, ionic strength and heat treatment temperature, which is mainly due to changes in surface hydrophobicity (H 0) and secondary structure, resulting in a reduction in protein molecular steric hindrance in an increase in molecular flexibility. This study demonstrated that combined ultrasound treatment and wet heating Maillard reaction could potentially be applied as a method to prepare 7S-MD conjugates. © 2013 Springer-Verlag Berlin Heidelberg.

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