Replacement of an amino acid residue of cyclodextrin glucanotransferase of Bacillus ohbensis doubles the production of gamma-cyclodextrin.
Cyclodextrin glucanotransferase (CGTase; EC 2.4.1.19) produces cyclodextrin (CD) from starch through an intramolecular transglucosylation reaction. To obtain a better understanding of the amylolytic and cyclization mechanisms of CGTase, and furthermore to improve the production of gamma-CD, mutant CGTases were constructed by site-directed mutagenesis of the CGTase gene of Bacillus ohbensis replacing Tyr at position 188 by 19 other amino acids. All mutant enzymes retained both starch-degrading and CD synthesizing activities to various extents. Among them, a mutant enzyme having Trp instead of Tyr-188 produced 15% of gamma-CD from soluble starch, which is about twice as much as the amount produced by the wild-type enzyme.
Sin
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KA
Department of Biotechnology, Faculty of Agriculture, University of Tokyo, Japan.
Nakamura
A
A
Masaki
H
H
Matsuura
Y
Y
Uozumi
T
T
D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D003505:Cyclodextrins / Q000096:biosynthesis*; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D013329:Structure-Activity Relationship; D047408:gamma-Cyclodextrins
D003505:Cyclodextrins; D047408:gamma-Cyclodextrins; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase; C023792:gamma-cyclodextrin