Wang L, Xia Y, Su L, Wu J. Modification of
Bacillus clarkii γ-Cyclodextrin Glycosyltransferase and Addition of Complexing Agents to Increase γ-Cyclodextrin Production.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020;
68:12079-12085. [PMID:
33052686 DOI:
10.1021/acs.jafc.0c05408]
[Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
γ-Cyclodextrin (γ-CD), a cyclic oligosaccharide containing eight glucose units linked by α-1,4-glycosidic bonds, can be produced from starch using cyclodextrin glycosyltransferase (CGTase). Unfortunately, this enzymatic process produces mixtures of α-, β-, and γ-CD. In this study, amino acid residues in the subsite -3 (T47 and F91) and the central subsite (Y186) of Bacillus clarkii γ-CGTase were modified to improve the γ-CD production. The cyclization activities and product specificities of mutants T47H and F91W were similar to those of the wild-type. The cyclization activities of mutants F91N and F91L were significantly greater than those of the wild-type but their γ-CD product specificities were lower. Finally, the central subsite mutant Y186W displayed a γ-CD specificity (94.6%) significantly greater than that of the wild-type (77.1%). To maximize the γ-CD yield, the effects of added complexing agents were investigated. Among the cyclic complexing agents tested, low-boiling cyclododecanone was the smallest that precipitated with γ-CD. When cyclododecanone was used with Y186W, the total CD yield reached 72.6%, and 96.6% of the product was γ-CD. These results, which represent the highest γ-CD yield ever reported, may provide a way to improve large-scale γ-CD preparation and expand the uses of γ-CD in the future.
Collapse