Influence of pH on the Structure and Function of Kiwi Pectin Methylesterase Inhibitor

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• 作者：Alessandro Bonavita ; Vitale Carratore ; Maria Antonietta Ciardiello ; Alfonso Giovane ; Luigi Servillo ; Rossana D’Avino
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2016
• 出版时间：July 27, 2016
• 年：2016
• 卷：64
• 期：29
• 页码：5866-5876
• 全文大小：430K
• 年卷期：0
• ISSN：1520-5118

文摘

Pectin methylesterase is a pectin modifying enzyme that plays a key role in plant physiology. It is also an important quality-related enzyme in plant-based food products. The pectin methylesterase inhibitor (PMEI) from kiwifruit inhibits this enzyme activity and is widely used as an efficient tool for research purposes and also recommended in the context of fruit and vegetable processing. Using several methodologies of protein biochemistry, including circular dichroism and fluorescence spectroscopy, chemical modifications, direct protein-sequencing, enzyme activity, and bioinformatics analysis of the crystal structure, this study demonstrates that conformational changes occur in kiwi PMEI by the pH rising over 6.0 bringing about structure loosening, exposure, and cleavage of a natively buried disulfide bond, unfolding and aggregation, ultimately determining the loss of ability of kiwi PMEI to bind and inhibit PME. pH-induced structural changes are prevented when PMEI is already engaged in complex or is in a solution of high ionic strength.