Download MendeleyCrystal structure of alkalophilic asparagine 233-replaced cyclodextrin glucanotransferase complexed with an inhibitor, acarbose, at 2.0 A resolution.
Ishii, N., Haga, K., Yamane, K., Harata, K.(2000) J Biochem 127: 383-391
- PubMed: 10731709
- DOI: https://doi.org/10.1093/oxfordjournals.jbchem.a022619
- Primary Citation of Related Structures:
1DED - PubMed Abstract:
The product specificity of cyclodextrin glucanotransferase (CGTase) from alkalophilic Bacillus sp. #1011 is improved to near-uniformity by mutation of histidine-233 to asparagine. Asparagine 233-replaced CGTase (H233N-CGTase) no longer produces alpha-cyclodextrin, while the wild-type CGTase from the same bacterium produces a mixture of predominantly alpha-, beta-, and gamma-cyclodextrins, catalyzing the conversion of starch into cyclic or linear alpha-1,4-linked glucopyranosyl chains. In order to better understand the protein engineering of H233N-CGTase, the crystal structure of the mutant enzyme complexed with a maltotetraose analog, acarbose, was determined at 2.0 A resolution with a final crystallographic R value of 0.163 for all data. Taking a close look at the active site cleft in which the acarbose molecule is bound, the most probable reason for the improved specificity of H233N-CGTase is the removal of interactions needed to form a compact ring like a-cyclodextrin.
Organizational Affiliation:
Biophysical Chemistry Laboratory, National Institute of Bioscience and Human-Technology, Tsukuba, Ibaraki 305-8566, Japan. ishii@nibh.go.jp.
