Abstract

Dextranase catalyzes the hydrolysis of the alpha-1,6-glycosidic linkage in dextran polymers. The structure of dextranase, Dex49A, from Penicillium, minioluteum was solved in the apo-enzyme and product-bound forms. The main domain of the enzyme is a right-handed parallel beta helix, which is connected to a beta sandwich domain at the N terminus. In the structure of the product complex, isomaltose was found to bind in a crevice on the surface of the enzyme. The glycosidic oxygen of the glucose unit in subsite +1 forms a hydrogen bond to the suggested catalytic acid, Asp395. By NMR spectroscopy the reaction course was shown to occur with net inversion at the anomeric carbon, implying a single displacement mechanism. Both Asp376 and Asp396 are suitably positioned to activate the water molecule that performs the nucleophilic attack. A new clan that links glycoside hydrolase families 28 and 49 is suggested

Published in

Structure
2003, Volume: 11, number: 9, pages: 1111-1121
Publisher: CELL PRESS

SLU Authors

• Kenne, Lennart

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Andersson, Rolf

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Ståhlberg, Jerry

  • Department of Molecular Biology, Swedish University of Agricultural Sciences
    

Publication identifier

DOI: https://doi.org/10.1016/S0969-2126(03)00147-3

Permanent link to this page (URI)

https://res.slu.se/id/publ/580