Jiangnan University

Yuxiang Bai

Zhengyu Jin

Xing Zhou

Zhengjun Xie

Yaoqi Tian

Xueming Xu

Long Chen

Jinpeng Wang

Jie Long

Chao Qiu

Xingfei Li

Liuxi Xia

Yun Wu

Ziying Ye

Xiaoxiao Li

Cheng Lu

Disclosed are an agarase mutant with improved thermal stability and application thereof, belonging to the fields of genetic engineering technology and enzyme engineering. The present disclosure provides an agarase mutant, which is obtained by mutating the amino acid at the 86site, the 373site, the 374site, the 496site, the 507site, or the 747site of agarase with an amino acid sequence as shown in SEQ ID NO. 1. The agarase mutant provided by the present disclosure improves the thermal stability and the hydrolytic activity of the agarase. Compared with the wild type enzyme, the mutant enzyme shows excellent heat resistance and can be industrially used at a relatively high temperature, so that the utilization rate of agar raw materials and the yield of oligosaccharides from agar are improved, and the mutant enzyme has a good industrial application prospect.

Agarase mutant with improved thermal stability and application thereof

The disclosure herein relates to a method for reducing the inhibitory effect of a cyclodextrin on a pullulanase and belongs to the technical field of gene engineering, enzyme engineering or food science. The method of the disclosure prepares a pullulanase mutant by reasonably mutating the key amino acid of the pullulanase interactive with the cyclodextrin to reduce the inhibitory effect of the cyclodextrin on the pullulanase, thereby improving the hydrolysis activity of the pullulanase. The disclosure finds the interactive sites of the pullulanase and the cyclodextrin based on analysis of crystal structures of enzymes and inhibitors and sequence comparison of enzymes from different sources, and utilizes site-directed mutation to obtain the pullulanase mutant having reduced sensibility to the cyclodextrin, thereby improving the utilization ratio of the starch raw material and the yield of the cyclodextrin.

Pullulanase mutant

The disclosure herein relates to a method for preparing branched cyclodextrin and application thereof, and belongs to the technical field of synthesis of branched cyclodextrin. The method comprises the following steps: (1) dissolving maltodextrin in a phosphate buffer solution, and adding CGTase for reacting; (2) reducing enzyme activity by a physical method; and (3) adding a saccharifying enzyme to the reaction system of step (2), and performing high-temperature enzyme deactivation to obtain the branched cyclodextrin. The method has mild reaction conditions, and at the same time, cyclodextrin and unreacted substrates can be hydrolyzed via the weak coupling activity of CGTase, thereby realizing effective separation of the branched cyclodextrin.

Method for preparing branched cyclodextrin and application thereof

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Wuxi, China

Yuxiang Bai