Dijkhuizen, L

Dijkstra, BW

Kalk, KH

Uitdehaag, JCM

English

The enzyme cyclodextrin glycosyltransferase is closely related to alpha-amylases but has the unique ability to produce cyclodextrins (circular alpha(1--&gt;4)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-Angstrom structure of an E257Q/D229N mutant cyclodextrin glycosyltransferase in complex with its product gamma-cyclodextrin, which reveals for the first time how cyclodextrin is competently bound. Across subsites -2, -1, and fl, the cyclodextrin ring binds in a twisted mode similar to linear sugars, giving rise to deformation of its circular symmetry. At subsites -3 and +2, the cyclodextrin binds in a manner different from linear sugars. Sequence comparisons and site-directed mutagenesis experiments support the conclusion that subsites -3 and +2 confer the cyclization activity in addition to subsite -6 and Tyr-195, On this basis, a role of the individual residues during the cyclization reaction cycle is proposed.</p

Proceedings - University of Groningen

The cyclization mechanism of cyclodextrin glycosyltransferase (CGTase) as revealed by a gamma-cyclodextrin-CGTase complex at 1.8-angstrom resolution

https://pure.rug.nl/ws/files/71289661/The_cyclization_mechanism_of_cyclodextrin_glycosyltransferase_CGTase_as_revealed_by_a_gamma_cyclodextrin_CGTase_complex_at_1.8_angstrom_resolution.pdf

The cyclization mechanism of cyclodextrin glycosyltransferase (CGTase) as revealed by a gamma-cyclodextrin-CGTase complex at 1.8-angstrom resolution

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Proceedings - University of Groningen