Changes in inhibitory activity and secondary conformation of soybean trypsin inhibitors induced by tea polyphenol complexation |
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| Authors: | Huihua Huang Mouming Zhao Qilong Ren Yiwen Yang |
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| Affiliation: | 1. Department of Food Science and Technology, South China University of Technology, Guangzhou, China;2. College of Material Science and Chemical Engineering, Zhejiang University, Hangzhou, China |
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| Abstract: | BACKGROUND: Tea polyphenol (TP) is a new food additive for antioxidant application, while soybean is an important resource for food and feed processing. It is therefore of rational and practical significance to investigate the influence of TP on soybean trypsin inhibitors (TIs). The aim of this study was to determine the effects of TP on the inhibitory activity of Kunitz (KTI) and Bowman–Birk (BBTI) TIs and to reveal the relationship between the inhibitory activity and conformation of KTI and BBTI by measurement of circular dichroism (CD) spectra. RESULTS: KTI and BBTI were found to be partially deactivated by TP. BBTI exhibited stronger resistance than KTI to TP deactivation. The unchanged KM value of trypsin for benzoyl‐DL ‐arginine‐p‐nitroanilide hydrolysis indicated that KTI and BBTI inhibited trypsin in a non‐competitive pattern when complexed with TP. As the TP/TI ratio was increased and the inhibitory activity of KTI and BBTI decreased, the conformation of KTI and BBTI showed relevant changes and the major CD negative bands shifted progressively towards the near‐UV region. CONCLUSION: These results show the deactivation effects of TP on KTI and BBTI and reveal preliminarily the relationship between the inhibitory activity and secondary structure of KTI and BBTI. Copyright © 2009 Society of Chemical Industry |
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| Keywords: | soybean trypsin inhibitor complexation tea polyphenol inhibitory activity conformation circular dichroism |
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