1CGU

CATALYTIC CENTER OF CYCLODEXTRIN GLYCOSYLTRANSFERASE DERIVED FROM X-RAY STRUCTURE ANALYSIS COMBINED WITH SITE-DIRECTED MUTAGENESIS

Summary for 1CGU

• Entry DOI: 10.2210/pdb1cgu/pdb
• Related PRD ID: PRD_900001
• Descriptor: CYCLODEXTRIN GLYCOSYL-TRANSFERASE, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, CALCIUM ION, ... (4 entities in total)
• Functional Keywords: glycosyltransferase
• Biological source: Bacillus circulans
• Total number of polymer chains: 1
• Total formula weight: 74943.48

Authors

Klein, C.,Hollender, J.,Bender, H.,Schulz, G.E. (deposition date: 1992-06-10, release date: 1994-01-31, Last modification date: 2024-10-16)

Primary citation

Klein, C.,Hollender, J.,Bender, H.,Schulz, G.E.
Catalytic center of cyclodextrin glycosyltransferase derived from X-ray structure analysis combined with site-directed mutagenesis.
Biochemistry, 31:8740-8746, 1992

PubMed Abstract: An X-ray structure analysis of a crystal of mutant Asp229----Ala of cyclodextrin glycosyltransferase from Bacillus circulans (Ec 2.4.1.19) 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.

PubMed: 1390660
DOI: 10.1021/bi00152a009

Experimental method

X-RAY DIFFRACTION (2.5 Å)