Cyclodextrin glucosyltransferase (CGTase) can convert starch to cyclodextrins, including α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and γ-cyclodextrins (γ-CD). Among these cyclodextrins, α-CD has characteristics of low yield and easy degradation. In this study, a CGTase derived from Bacillus stearothermophilus NO2 was selected and the α-CD producing ability of its mutants, including E142P, L277M, L277F, E142P/L277M, E142P/L277F, L277M/N353A, and L277F/N353A, were measured using soluble starch as substrate. Compared with the wild-type, the optimal mutant E142P/L277M increased the yield of α-CD by 1.7 g/L and the proportion of α-CD in the product increased by 14.3%. Molecular dynamics (MD) simulation results showed that the influence between the sites of E142 and L277 in E142P/L277M mutant was slight. In addition, the catalytic effect of L277M/N353A was poor, and MD results showed that the overall structure of L277M/N353A was changed greatly and its SASA was increased, which were not conducive to the occurrence of transglycoside reaction. This paper provides a new idea for the molecular modification of CGTase to improve the activity of cyclization reaction and increase the yield of CGTase in the industrial production of α-CD.
KONG Demin
,
ZUO Fangyuan
,
WU Jing
,
WANG Lei
. Improvement of α-cyclodextrin yield by mutants of Leu277 about CGTase from Bacillus stearothermophilus NO2[J]. Food and Fermentation Industries, 2023
, 49(15)
: 1
-7
.
DOI: 10.13995/j.cnki.11-1802/ts.034278
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