ISSN:
0887-3585
Keywords:
DEX gene
;
dextranase
;
protein threading
;
structure prediction
;
circular dichroism
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The DEX gene encodes an extracellular dextranase (EC 3.2.1.11); this enzyme hydrolyzes the α(1,6) glucosidic bond contained in dextran to release small isomaltosaccharides. Sequence analysis has revealed only one homologous sequence, CB-8 protein, from Arthrobacter sp., with 30% sequence identity. The secondary structure prediction for Dex was corroborated by circular dichroism measurements. To explore the possibility that Dex protein might adopt a fold similar to any known structure, we conducted a threading search of a three-dimensional structure database. This search revealed that the Dex sequence is compatible with the galactose oxidase/methanol dehydrogenase/sialidase fold. A structural model of Dex based on these results is physically and biologically plausible and leads to testable predictions, including the prediction that Asp246 and Glu299 might be catalytic residues. Also, according to this model the Dex enzyme has a mechanism of hydrolysis with net inversion of anomeric configuration. Proteins 31:345-354, 1998. © 1998 Wiley-Liss, Inc.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
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