Leu600 mutations decrease product inhibition of the β-cyclodextrin glycosyltransferase from Bacillus circulans STB01
Leu600 mutations decrease product inhibition of the β-cyclodextrin glycosyltransferase from Bacillus circulans STB01
复制标题
Leu600 突变降低了环状芽孢杆菌 STB01 β-环糊精糖基转移酶的产物抑制
DOI：
10.1016/j.ijbiomac.2018.05.006
复制
发表时间：
2018-08-01
影响因子：
8.2
通讯作者：
Li, Caiming
中科院分区：
文献类型：
--
作者：
Chen, Shuangdi;Li, Zhaofeng;Li, Caiming
The limits that cyclodextrin products impose on their industrial production from starch by cyclodextrin glycosyl-transferases (CGTases) are a severe problem. In this paper, mutants at residue Leu600 of the beta-CGTase from Bacillus circulans STB01 were constructed in an effort to decrease the product inhibition exhibited by beta-cyclodextrin. A kinetic analysis of the inhibition of the wild-type and mutant beta-CGTases by beta-cyclodextrin revealed that the mutations do not alter the inhibition mode, which is mixed-type. However, the values of the inhibition constants (K-i and K-i') of the mutants L600I, L600E and L600R are higher than those of the wild-type enzyme, weakening the product inhibition. The mutant L600Y only exhibited a decrease in noncompetitive inhibition, with the value of Ki' increasing by 40%. Comparison of the K-m' values and the 3D model structures of the wild-type and mutant CGTases suggests that this decrease in product inhibition is related to a decrease in binding affinity between the product cyclodextrin and the enzyme. (C) 2018 Elsevier B.V. All rights reserved.
