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1xys

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{{STRUCTURE_1xys| PDB=1xys | SCENE= }}
{{STRUCTURE_1xys| PDB=1xys | SCENE= }}
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'''CATALYTIC CORE OF XYLANASE A E246C MUTANT'''
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===CATALYTIC CORE OF XYLANASE A E246C MUTANT===
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==Overview==
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BACKGROUND: Sequence alignment suggests that xylanases evolved from two ancestral proteins and therefore can be grouped into two families, designated F and G. Family F enzymes show no sequence similarity with any known structure and their architecture is unknown. Studies of an inactive enzyme-substrate complex will help to elucidate the structural basis of binding and catalysis in the family F xylanases. RESULTS: We have therefore determined the crystal structure of the catalytic domain of a family F enzyme, Pseudomonas fluorescens subsp. cellulosa xylanase A, at 2.5 A resolution and a crystallographic R-factor of 0.20. The structure was solved using an engineered catalytic core in which the nucleophilic glutamate was replaced by a cysteine. As expected, this yielded both high-quality mercurial derivatives and an inactive enzyme which enabled the preparation of the inactive enzyme-substrate complex in the crystal. We show that family F xylanases are eight-fold alpha/beta-barrels (TIM barrels) with two active-site glutamates, one of which is the nucleophile and the other the acid-base. Xylopentaose binds to five subsites A-E with the cleaved bond between subsites D and E. Ca2+ binding, remote from the active-site glutamates, stabilizes the structure and may be involved in the binding of extended substrates. CONCLUSIONS: The architecture of P. fluorescens subsp. cellulosa has been determined crystallographically to be a commonly occurring enzyme fold, the eight-fold alpha/beta-barrel. Xylopentaose binds across the carboxy-terminal end of the alpha/beta-barrel in an active-site cleft which contains the two catalytic glutamates.
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{{ABSTRACT_PUBMED_7881909}}
==About this Structure==
==About this Structure==
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[[Category: Family 10 of glycosyl-hydrolase]]
[[Category: Family 10 of glycosyl-hydrolase]]
[[Category: Family f xylanase]]
[[Category: Family f xylanase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 13:25:49 2008''

Revision as of 10:25, 28 July 2008

Image:1xys.png

Template:STRUCTURE 1xys

CATALYTIC CORE OF XYLANASE A E246C MUTANT

Template:ABSTRACT PUBMED 7881909

About this Structure

1XYS is a Single protein structure of sequence from Cellvibrio japonicus. Full crystallographic information is available from OCA.

Reference

Structure of the catalytic core of the family F xylanase from Pseudomonas fluorescens and identification of the xylopentaose-binding sites., Harris GW, Jenkins JA, Connerton I, Cummings N, Lo Leggio L, Scott M, Hazlewood GP, Laurie JI, Gilbert HJ, Pickersgill RW, Structure. 1994 Nov 15;2(11):1107-16. PMID:7881909

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