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1rwc

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{{STRUCTURE_1rwc| PDB=1rwc | SCENE= }}
{{STRUCTURE_1rwc| PDB=1rwc | SCENE= }}
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'''Crystal structure of Arthrobacter aurescens chondroitin AC lyase'''
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===Crystal structure of Arthrobacter aurescens chondroitin AC lyase===
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==Overview==
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Chondroitin lyases (EC 4.2.2.4 and EC 4.2.2.5) are glycosaminoglycan-degrading enzymes that act as eliminases. Chondroitin lyase AC from Arthrobacter aurescens (ArthroAC) is known to act on chondroitin 4-sulfate and chondroitin 6-sulfate but not on dermatan sulfate. Like other chondroitin AC lyases, it is capable of cleaving hyaluronan. We have determined the three-dimensional crystal structure of ArthroAC in its native form as well as in complex with its substrates (chondroitin 4-sulfate tetrasaccharide, CS(tetra) and hyaluronan tetrasaccharide) at resolution varying from 1.25 A to 1.9A. The primary sequence of ArthroAC has not been previously determined but it was possible to determine the amino acid sequence of this enzyme from the high-resolution electron density maps and to confirm it by mass spectrometry. The enzyme-substrate complexes were obtained by soaking the substrate into the crystals for varying lengths of time (30 seconds to ten hours) and flash-cooling the crystals. The electron density map for crystals soaked in the substrate for as short as 30 seconds showed the substrate clearly and indicated that the ring of central glucuronic acid assumes a distorted boat conformation. This structure strongly supports the lytic mechanism where Tyr242 acts as a general base that abstracts the proton from the C5 position of glucuronic acid while Asn183 and His233 neutralize the charge on the glucuronate acidic group. Comparison of this structure with that of chondroitinase AC from Flavobacterium heparinum (FlavoAC) provides an explanation for the exolytic and endolytic mode of action of ArthroAC and FlavoAC, respectively.
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(as it appears on PubMed at http://www.pubmed.gov), where 15003453 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15003453}}
==About this Structure==
==About this Structure==
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[[Category: Chondroitinase]]
[[Category: Chondroitinase]]
[[Category: Hyaluronan]]
[[Category: Hyaluronan]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 07:59:03 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 02:45:30 2008''

Revision as of 23:45, 28 July 2008

Image:1rwc.png

Template:STRUCTURE 1rwc

Crystal structure of Arthrobacter aurescens chondroitin AC lyase

Template:ABSTRACT PUBMED 15003453

About this Structure

Full crystallographic information is available from OCA.

Reference

High-resolution crystal structure of Arthrobacter aurescens chondroitin AC lyase: an enzyme-substrate complex defines the catalytic mechanism., Lunin VV, Li Y, Linhardt RJ, Miyazono H, Kyogashima M, Kaneko T, Bell AW, Cygler M, J Mol Biol. 2004 Mar 19;337(2):367-86. PMID:15003453

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