Modification of AnidAgdB and its application in the preparation of indigestible dextrin
Indigestible dextrin is a general term for a group of soluble dextrin rich in α-1,2,α-1,3,α-1,6 glycosidic bonds or cyclic sugar chain structure,which are characterized by a low glycemic index and the promotion of the proliferation of intestinal probiotics.Cur-rently,the mainstream commercial preparation process of indigestible dextrin is the acid-heat method,and there are still few studies on the enzymatic preparation of indigestible dextrin.The key to the preparation of indigestible dextrin is to increase the content of indigestible α-1,2,α-1,3,and α-1,6 glycosidic bonds or to increase the degree of product polymerization.AgdB,an α-glucosidase of Aspergillus nidu-lans origin,was modified to increase its product α-1,3 bond type or to increase its product polymerization.A total of four mutants,N466D,R450H,A445S,and Y202A,were obtained by rational design after targeted mutagenesis.Upon reaction with maltose as sub-strate,the α-1,3 glycosidic bond content of the products of mutants N466D,R450H increased,and higher polymerization degree of the products was generated by mutants R450H,A445S,and Y202A.Subsequently,the mutant and wild type were complexed with cyclodex-trin glucosyltransferase,respectively,and the results showed that mutants R450H,A445S,and Y202A were all effective in increasing the slow-digestible composition of the products,and mutant N466D increased the α-1,3 bond content but also increased the α-1,4 bond con-tent,so that the slow-digestible composition of the products was instead reduced.This study provides a new idea for modifying α-glucosi-dase to improve the slow-digesting and anti-digesting components of indigestible dextrin.
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维普
