Catalytic center of cyclodextrin glycosyltransferase derived from X-ray structure analysis combined with site-directed mutagenesis.Klein, C., Hollender, J., Bender, H., Schulz, G.E.
(1992) Biochemistry 31: 8740-8746
- PubMed: 1390660
- PubMed Abstract:
- Molecular Cloning, Nucleotide Sequence and Expression in Escherichia Coli of the Beta-Cyclodextrin Glycosyltransferase Gene from Bacillus Circulans Strain No. 8
Nitschke, L.,Heeger, K.,Bender, H.,Schulz, G.E.
(1990) Appl.Microbiol.Biotechnol. 33: 542
- Structure of Cyclodextrin Glycosyltransferase Refined at 2.0 Angstroms Resolution
Klein, C.,Schulz, G.E.
(1991) J.Mol.Biol. 217: 737
- Three-Dimensional Structure of Cyclodextrin Glycosyltransferase from Bacillus Circulans at 3.4 Angstroms Resolution
Hofmann, B.E.,Bender, H.,Schulz, G.E.
(1989) J.Mol.Biol. 209: 793
- Engineering a Heavy Atom Derivative for the X-Ray Structure Analysis of Cyclodextrin Glycosyltransferase
Klein, C.,Vogel, W.,Bender, H.,Schulz, G.E.
(1990) Protein Eng. 4: 65
An X-ray structure analysis of a crystal of mutant Asp229----Ala of cyclodextrin glycosyltransferase from Bacillus circulans (Ec 22.214.171.124) that had been shortly exposed to beta-cyclodextrin showed density corresponding to a maltose bound at the catal ...
An X-ray structure analysis of a crystal of mutant Asp229----Ala of cyclodextrin glycosyltransferase from Bacillus circulans (Ec 126.96.36.199) that had been shortly exposed to beta-cyclodextrin showed density corresponding to a maltose bound at the catalytic center. The crystal structure was refined to an R-factor of 18.7% at 2.5-A resolution. The catalytic center is defined by homology with the structurally known alpha-amylases and by the observation that mutants Asp229----Ala and Asp328----Ala are almost inactive. By model building, the density-defined maltose was extended to a full beta-cyclodextrin, which then indicated the general locations of seven subsites for glucosyl units. The catalytically competent residues Asp229, Glu257, and Asp328 are at the reducing end of the density-defined maltose. In the unligated wild-type structure, Glu257 and Asp328 form a 2.6-A hydrogen bond between their carboxylates in an arrangement that resembles those of the catalytically competent carboxylates in acid proteases. Presumably, the first catalytic step is an attack of the proton between Glu257 and Asp328 on the oxygen of the glycosidic bond.
Institut für Organische Chemie und Biochemie, Universität, Freiburg im Breisgau, Germany.