Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour
Endogenous α-amylase activity is crucial for determining the end-use value of glutinous rice flour (GRF), and controlling it is a key goal in the milling process. Although the structure and properties of starch and protein in GRF have been extensively studied, there is little information on endogeno...
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2025-05-01
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| author | Huang Zhang Fengjiao Zhang Fengfeng Wu Lichun Guo Xueming Xu |
| author_facet | Huang Zhang Fengjiao Zhang Fengfeng Wu Lichun Guo Xueming Xu |
| author_sort | Huang Zhang |
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| description | Endogenous α-amylase activity is crucial for determining the end-use value of glutinous rice flour (GRF), and controlling it is a key goal in the milling process. Although the structure and properties of starch and protein in GRF have been extensively studied, there is little information on endogenous α-amylase in GRF. In this study, endogenous α-amylase isolated from GRF was purified and characterized. It was found to have a molecular weight of about 32 kDa, with the highest specific activity at 60 °C and a pH of 6.0. The enzyme is stable below 50 °C and in the pH range of 4.0–7.0. Its activity is Ca<sup>2</sup>⁺-independent but inhibited by Cu<sup>2</sup>⁺, Zn<sup>2</sup>⁺, Mg<sup>2</sup>⁺, Mn<sup>2</sup>⁺, and Ba<sup>2</sup>⁺. Its activity is also reduced by β-mercaptoethanol. The enzyme hydrolyzes amylopectin most efficiently. Circular dichroism spectroscopy showed that the enzyme contains 7.9% α-helix, 35.4% β-folding, 21.1% β-turning, and 35.9% random coils, with a T<sub>m</sub> value of 63.68 °C. These results suggest that temperature control may be the best strategy for reducing amylase activity in dry-milled GRF, providing a new approach for the development of GRF dry-milling techniques. |
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| spelling | doaj-art-7f81d5a8eb21469f82e13fef483cbb722025-08-20T01:56:19ZengMDPI AGFoods2304-81582025-05-011410167910.3390/foods14101679Purification and Characterization of Endogenous α-Amylase from Glutinous Rice FlourHuang Zhang0Fengjiao Zhang1Fengfeng Wu2Lichun Guo3Xueming Xu4College of Food and Biological Engineering, Henan University of Animal Husbandry and Economy, No. 6, Longzihu North Road, Zhengzhou 450046, ChinaCollege of Food and Biological Engineering, Henan University of Animal Husbandry and Economy, No. 6, Longzihu North Road, Zhengzhou 450046, ChinaThe State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi 214122, ChinaThe State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi 214122, ChinaThe State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi 214122, ChinaEndogenous α-amylase activity is crucial for determining the end-use value of glutinous rice flour (GRF), and controlling it is a key goal in the milling process. Although the structure and properties of starch and protein in GRF have been extensively studied, there is little information on endogenous α-amylase in GRF. In this study, endogenous α-amylase isolated from GRF was purified and characterized. It was found to have a molecular weight of about 32 kDa, with the highest specific activity at 60 °C and a pH of 6.0. The enzyme is stable below 50 °C and in the pH range of 4.0–7.0. Its activity is Ca<sup>2</sup>⁺-independent but inhibited by Cu<sup>2</sup>⁺, Zn<sup>2</sup>⁺, Mg<sup>2</sup>⁺, Mn<sup>2</sup>⁺, and Ba<sup>2</sup>⁺. Its activity is also reduced by β-mercaptoethanol. The enzyme hydrolyzes amylopectin most efficiently. Circular dichroism spectroscopy showed that the enzyme contains 7.9% α-helix, 35.4% β-folding, 21.1% β-turning, and 35.9% random coils, with a T<sub>m</sub> value of 63.68 °C. These results suggest that temperature control may be the best strategy for reducing amylase activity in dry-milled GRF, providing a new approach for the development of GRF dry-milling techniques.https://www.mdpi.com/2304-8158/14/10/1679glutinous rice flourendogenous α-amylasepurificationcharacterization |
| spellingShingle | Huang Zhang Fengjiao Zhang Fengfeng Wu Lichun Guo Xueming Xu Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour Foods glutinous rice flour endogenous α-amylase purification characterization |
| title | Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour |
| title_full | Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour |
| title_fullStr | Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour |
| title_full_unstemmed | Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour |
| title_short | Purification and Characterization of Endogenous α-Amylase from Glutinous Rice Flour |
| title_sort | purification and characterization of endogenous α amylase from glutinous rice flour |
| topic | glutinous rice flour endogenous α-amylase purification characterization |
| url | https://www.mdpi.com/2304-8158/14/10/1679 |
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