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The structural basis for catalysis and specificity of the Pseudomonas cellulosa alpha-glucuronidase, GlcA67A

Lookup NU author(s): Tibor Nagy, Emeritus Professor Harry Gilbert

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Abstract

alpha-glucuronidases, components of an ensemble of enzymes central to the recycling of photosynthetic biomass, remove the alpha-1,2 linked 4-O-methyl glucuronic acid from xylans. The structure of the alpha-glucuronidase, GlcA67A, from Pseudomonas cellulosa reveals three domains, the central of which is a (beta/alpha)(B) barrel housing the catalytic apparatus. Complexes of the enzyme with the individual reaction products, either xylobiose or glucuronic acid, and the ternary complex of both glucuronic acid and xylotriose reveal a "blind" pocket which selects for short decorated xylooligosaccharides substituted with the uronic acid at their nonreducing end, consistent with kinetic data. The catalytic center reveals a constellation of carboxylates; Glu292 is poised to provide protonic assistance to leaving group departure with Glu393 and Asp365 both appropriately positioned to provide base-catalyzed assistance for inverting nucleophilic attack by water.

Publication metadata

Author(s): Nurizzo D, Nagy T, Gilbert HJ, Davies GJ

Publication type: Article

Publication status: Published

Journal: Structure

Year: 2002

Volume: 10

Issue: 4

Pages: 547-556

ISSN (print): 0969-2126

ISSN (electronic): 1878-4186

Publisher: Cell Press

URL: http://dx.doi.org/10.1016/S0969-2126(02)00742-6

DOI: 10.1016/S0969-2126(02)00742-6

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