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1ofl

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[[Image:1ofl.gif|left|200px]]
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{{STRUCTURE_1ofl| PDB=1ofl | SCENE= }}
{{STRUCTURE_1ofl| PDB=1ofl | SCENE= }}
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'''CRYSTAL STRUCTURE OF CHONDROITINASE B COMPLEXED TO DERMATAN SULFATE HEXASACCHARIDE'''
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===CRYSTAL STRUCTURE OF CHONDROITINASE B COMPLEXED TO DERMATAN SULFATE HEXASACCHARIDE===
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==Overview==
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Chondroitinase B from Pedobacter heparinus is the only known enzyme strictly specific for dermatan sulfate and is a widely used enzymatic tool for the structural characterization of glycosaminoglycans. This beta-helical polysaccharide lyase belongs to family PL-6 and cleaves the beta(1,4) linkage of dermatan sulfate in a random manner, yielding 4,5-unsaturated dermatan sulfate disaccharides as the product. The previously reported structure of its complex with a dermatan sulfate disaccharide product identified the -1 and -2 subsites of the catalytic groove. We present here the structure of chondroitinase B complexed with several dermatan sulfate and chondroitin sulfate oligosaccharides. In particular, the soaking of chondroitinase B crystals with a dermatan sulfate hexasaccharide results in a complex with two dermatan sulfate disaccharide reaction products, enabling the identification of the +2 and +1 subsites. Unexpectedly, this structure revealed the presence of a calcium ion coordinated by sequence-conserved acidic residues and by the carboxyl group of the l-iduronic acid at the +1 subsite. Kinetic and site-directed mutagenesis experiments have subsequently demonstrated that chondroitinase B absolutely requires calcium for its activity, indicating that the protein-Ca(2+)-oligosaccharide complex is functionally relevant. Modeling of an intact tetrasaccharide in the active site of chondroitinase B provided a better understanding of substrate specificity and the role of Ca(2+) in enzymatic activity. Given these results, we propose that the Ca(2+) ion neutralizes the carboxyl moiety of the l-iduronic acid at the cleavage site, whereas the conserved residues Lys-250 and Arg-271 act as Bronsted base and acid, respectively, in the lytic degradation of dermatan sulfate by chondroitinase B.
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(as it appears on PubMed at http://www.pubmed.gov), where 15155751 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15155751}}
==About this Structure==
==About this Structure==
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[[Category: Dematan sulfate]]
[[Category: Dematan sulfate]]
[[Category: Lyase]]
[[Category: Lyase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:47:12 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 08:26:56 2008''

Revision as of 05:26, 28 July 2008

Image:1ofl.png

Template:STRUCTURE 1ofl

CRYSTAL STRUCTURE OF CHONDROITINASE B COMPLEXED TO DERMATAN SULFATE HEXASACCHARIDE

Template:ABSTRACT PUBMED 15155751

About this Structure

1OFL is a Single protein structure of sequence from Pedobacter heparinus. Full crystallographic information is available from OCA.

Reference

The structure of chondroitin B lyase complexed with glycosaminoglycan oligosaccharides unravels a calcium-dependent catalytic machinery., Michel G, Pojasek K, Li Y, Sulea T, Linhardt RJ, Raman R, Prabhakar V, Sasisekharan R, Cygler M, J Biol Chem. 2004 Jul 30;279(31):32882-96. Epub 2004 May 21. PMID:15155751

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