Inactivation of Soybean Bowman-Birk Inhibitor by Stevioside: Interaction Studies and Application to Soymilk.

Chun Liu, Lijuan Luo, Ying Wu, Xiaoquan Yang, Jie Dong, Feijun Luo, Yuan Zou, Yingbin Shen, Qinlu Lin

Journal of agricultural and food chemistry 2019 Feb 27

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In this work, the interaction of the soybean Bowman-Birk inhibitor (BBI) with stevioside (STE) was studied by stopped-flow-fluorescence and molecular docking. STE's inactivation of protease-inhibitor activities in soymilk and the influence of STE addition on the sensory character of soymilk were also evaluated. The results indicate that STE binds BBI with a binding constant ( Ka) of 3.38 × 105 L mol-1 to form a 1:1 complex. The docking study reveals that two hydrogen bonds are formed between the side-chain of Lys16 (reactive site 1) of BBI and the glucose-ring hydroxyl groups of STE, which may block BBI from contacting trypsin and thus deactivate the trypsin-inhibitor activity (TIA) of BBI. Moreover, the residual TIA in soymilk could also be inactivated by STE. A mixture of 159 mg/L STE and 60 g/L sucrose could be used for sweetening soymilk without affecting the sensory characteristics when compared to a reference product sweetened with 9% sucrose.

Citation

Chun Liu, Lijuan Luo, Ying Wu, Xiaoquan Yang, Jie Dong, Feijun Luo, Yuan Zou, Yingbin Shen, Qinlu Lin. Inactivation of Soybean Bowman-Birk Inhibitor by Stevioside: Interaction Studies and Application to Soymilk. Journal of agricultural and food chemistry. 2019 Feb 27;67(8):2255-2264