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Biotechnology and Biological Transformations
Wheat starch with low retrogradation properties produced by modification of the GtfB enzyme 4,6-#-glucanotransferase from Streptococcus thermophilus Xiaolei Li, Teng Fei, Yong Wang, Yakun Zhao, Yutian Pan, and Dan Li J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b00550 • Publication Date (Web): 27 Mar 2018 Downloaded from http://pubs.acs.org on March 27, 2018
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Journal of Agricultural and Food Chemistry
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Wheat starch with low retrogradation properties produced by
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modification of the GtfB enzyme 4,6-α-glucanotransferase from
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Streptococcus thermophilus
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Xiaolei Li a,c, Teng Fei c, Yong Wang c, Yakun Zhao c, Yutian Pan a, Dan Li b,c *
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Running title: GtfB-modified wheat starch with low retrogradation properties
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a
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Science and Biotechnology, Minnan Normal University, 36 Xianqianzhi Street,
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Zhangzhou 363000, Fujian, People's Republic of China.
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b. College of Food and Biological Engineering, Jimei University, 43 Yindou Road,
Engineering Technological Center of Mushroom Industry, and School of Biological
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Xiamen 361021, Fujian, People's Republic of China.
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c
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Universities, Changchun University, 6543 Weixing Road, Changchun 130022, Jilin,
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People’s Republic of China.
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* Corresponding author. Tel.: +86 592 6181487; fax: +86 592 6180470.
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E-mail address:
[email protected] (D. Li).
Key Laboratory of Agro-products Processing Technology at Jilin Provincial
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
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ABSTRACT: A GtfB enzyme 4,6-α-glucanotransferase from Streptococcus
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thermophilus lacking 761 N-terminal amino acids, was heterologously expressed in
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Escherichia coli. Purified S. thermophilus GtfB showed transglycosylation activities
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towards starch, resulting in branch points of (α1→6)-glycosidic linkages plus linear
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chains of (α1→4)-glycosidic linkages. After wheat starch was modified at a rate of 0.1
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g/mL by 1–4 U/g starch GtfB at pH 6.0 and 40 °C for 1 h, the weight-averaged
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molecular weight decreased from 1.70 × 107 g/mol to 1.21 × 106–3.41 × 106 g/mol,
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the amylose content decreased from 22.07 to 16.34–17.11%, and that of amylopectin
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long branch chains decreased from 26.4 to 10.25–15.64% (P < 0.05). After the
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GtfB-modified wheat starches were gelatinized and stored at 4 °C for 1–2 weeks, their
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endothermic enthalpies were significantly lower than that of the control sample (P
