1czf: Difference between revisions
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'''ENDO-POLYGALACTURONASE II FROM ASPERGILLUS NIGER''' | '''ENDO-POLYGALACTURONASE II FROM ASPERGILLUS NIGER''' | ||
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[[Category: Kalk, K H.]] | [[Category: Kalk, K H.]] | ||
[[Category: Santen, Y van.]] | [[Category: Santen, Y van.]] | ||
[[Category: | [[Category: Beta helix]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:16:26 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 13:16, 2 May 2008
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| 1czf, resolution 1.68Å () | |||||||||
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| Ligands: | , | ||||||||
| Activity: | Polygalacturonase, with EC number 3.2.1.15 | ||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
ENDO-POLYGALACTURONASE II FROM ASPERGILLUS NIGER
OverviewOverview
Polygalacturonases specifically hydrolyze polygalacturonate, a major constituent of plant cell wall pectin. To understand the catalytic mechanism and substrate and product specificity of these enzymes, we have solved the x-ray structure of endopolygalacturonase II of Aspergillus niger and we have carried out site-directed mutagenesis studies. The enzyme folds into a right-handed parallel beta-helix with 10 complete turns. The beta-helix is composed of four parallel beta-sheets, and has one very small alpha-helix near the N terminus, which shields the enzyme's hydrophobic core. Loop regions form a cleft on the exterior of the beta-helix. Site-directed mutagenesis of Asp(180), Asp(201), Asp(202), His(223), Arg(256), and Lys(258), which are located in this cleft, results in a severe reduction of activity, demonstrating that these residues are important for substrate binding and/or catalysis. The juxtaposition of the catalytic residues differs from that normally encountered in inverting glycosyl hydrolases. A comparison of the endopolygalacturonase II active site with that of the P22 tailspike rhamnosidase suggests that Asp(180) and Asp(202) activate the attacking nucleophilic water molecule, while Asp(201) protonates the glycosidic oxygen of the scissile bond.
About this StructureAbout this Structure
1CZF is a Single protein structure of sequence from Aspergillus niger. Full crystallographic information is available from OCA.
ReferenceReference
1.68-A crystal structure of endopolygalacturonase II from Aspergillus niger and identification of active site residues by site-directed mutagenesis., van Santen Y, Benen JA, Schroter KH, Kalk KH, Armand S, Visser J, Dijkstra BW, J Biol Chem. 1999 Oct 22;274(43):30474-80. PMID:10521427 Page seeded by OCA on Fri May 2 13:16:26 2008