Leu600 mutations decrease product inhibition of the β-cyclodextrin glycosyltransferase from Bacillus circulans STB01
| Autor: | Caiming Li, Zhaofeng Li, Yan Hong, Li Cheng, Tod P. Holler, Zhengbiao Gu, Chen Shuangdi |
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| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
0301 basic medicine Models Molecular Protein Conformation Mutant Bacillus Cyclodextrin glycosyltransferase 01 natural sciences Biochemistry 03 medical and health sciences Non-competitive inhibition Structural Biology 010608 biotechnology Glycosyltransferase Enzyme Inhibitors Molecular Biology chemistry.chemical_classification Cyclodextrins Cyclodextrin biology General Medicine Kinetics 030104 developmental biology Enzyme chemistry Product inhibition Cyclization Glucosyltransferases Mutation Bacillus circulans biology.protein Mutagenesis Site-Directed |
| Zdroj: | International journal of biological macromolecules. 115 |
| ISSN: | 1879-0003 |
| Popis: | The limits that cyclodextrin products impose on their industrial production from starch by cyclodextrin glycosyltransferases (CGTases) are a severe problem. In this paper, mutants at residue Leu600 of the β-CGTase from Bacillus circulans STB01 were constructed in an effort to decrease the product inhibition exhibited by β-cyclodextrin. A kinetic analysis of the inhibition of the wild-type and mutant β-CGTases by β-cyclodextrin revealed that the mutations do not alter the inhibition mode, which is mixed-type. However, the values of the inhibition constants (Ki and Ki') 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 Km' 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. |
| Databáze: | OpenAIRE |
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