Catalytic activity enhancement of 1,4-α-glucan branching enzyme by N-terminal modification

Wenjuan Fan; Zhaofeng Li; Caiming Li; Zhengbiao Gu; Yan Hong; Li Cheng; Xiaofeng Ban

doi:10.1016/j.fochx.2023.100888

Catalytic activity enhancement of 1,4-α-glucan branching enzyme by N-terminal modification

Food Chem X. 2023 Sep 18:20:100888. doi: 10.1016/j.fochx.2023.100888. eCollection 2023 Dec 30.

Authors

Wenjuan Fan¹, Zhaofeng Li^{2

1

3}, Caiming Li¹, Zhengbiao Gu^{2

1

3

4}, Yan Hong¹, Li Cheng¹, Xiaofeng Ban^{2

1}

Affiliations

¹ School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
² State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
³ National Engineering Laboratory for Cereal Fermentation Technology, Wuxi, Jiangsu 214122, China.
⁴ Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China.

Abstract

The 1,4-α-glucan branching enzyme (GBE, EC 2.4.1.18) has garnered considerable attention for its ability to increase the degree of branching of starch and retard starch digestion, which has great industrial applications. Previous studies have reported that the N-terminal domain plays an important role in the expression and stability of GBEs. To further increase the catalytic ability of Gt-GBE, we constructed five mutants in the N-terminal domain: L19R, L19K, L25R, L25K, and L25A. Specific activities of L25R and L25A were increased by 28.46% and 23.46%, respectively, versus the wild-type Gt-GBE. In addition, the α-1,6-glycosidic linkage ratios of maltodextrin samples treated with L25R and L25A increased to 5.71%, which were significantly increased by 19.96% compared with that of the wild-type Gt-GBE. The results of this study suggest that the N-terminal domain selective modification can improve enzyme catalytic activity, thus further increasing the commercial application of enzymes in food and pharmaceutical industries.

Keywords: 1,4-α-glucan branching enzyme; Carbohydrate-binding module 48; Enzymatic activity; N-terminal domain; Salt bridge.