1chk: Difference between revisions

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[[Image:1chk.~~gif~~|left|200px]]

[[Image:1chk.png|left|200px]]

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~~'''~~STREPTOMYCES N174 CHITOSANASE PH5.5 298K~~'''~~

===STREPTOMYCES N174 CHITOSANASE PH5.5 298K===

~~==Overview==~~

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~~We report the 2.4 A X~~-~~ray crystal structure of a protein with chitosan endo~~-~~hydrolase activity isolated from Streptomyces N174.~~ The ~~structure was solved using phases acquired by SIRAS from a two-site methyl mercury derivative combined with solvent flattening and non-crystallographic two-fold symmetry averaging~~, ~~and refined~~ to ~~an R-factor of 18~~.5%. ~~The mostly alpha-helical fold reveals a structural core shared with several classes of lysozyme and barley endochitinase~~, in spite of a lack of shared sequence. Based on this structural similarity we postulate a putative active site, mechanism of action and mode of substrate recognition. It appears that Glu 22 acts as an acid and Asp 40 serves as a general base to activate a water molecule for an SN2 attack on the ~~glycosidic bond~~. ~~A series of amino~~-~~acid side chains and backbone carbonyl groups may bind the polycationic chitosan substrate in a deep electronegative binding cleft.~~

The line below this paragraph, {{ABSTRACT_PUBMED_8564542}}, adds the Publication Abstract to the page

(as it appears on PubMed at http://www.pubmed.gov), where 8564542 is the PubMed ID number.

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==About this Structure==

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[[Category: Hydrolase]]

[[Category: O-glycosyl]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on ~~Fri May 2 12~~:44:18 2008''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 20:45:18 2008''

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-[[Image:1chk.gif|left|200px]]
+{{Seed}}
+[[Image:1chk.png|left|200px]]
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 {{STRUCTURE_1chk|  PDB=1chk  |  SCENE=  }}
-'''STREPTOMYCES N174 CHITOSANASE PH5.5 298K'''
+===STREPTOMYCES N174 CHITOSANASE PH5.5 298K===
-==Overview==
+<!--
-We report the 2.4 A X-ray crystal structure of a protein with chitosan endo-hydrolase activity isolated from Streptomyces N174. The structure was solved using phases acquired by SIRAS from a two-site methyl mercury derivative combined with solvent flattening and non-crystallographic two-fold symmetry averaging, and refined to an R-factor of 18.5%. The mostly alpha-helical fold reveals a structural core shared with several classes of lysozyme and barley endochitinase, in spite of a lack of shared sequence. Based on this structural similarity we postulate a putative active site, mechanism of action and mode of substrate recognition. It appears that Glu 22 acts as an acid and Asp 40 serves as a general base to activate a water molecule for an SN2 attack on the glycosidic bond. A series of amino-acid side chains and backbone carbonyl groups may bind the polycationic chitosan substrate in a deep electronegative binding cleft.
+The line below this paragraph, {{ABSTRACT_PUBMED_8564542}}, adds the Publication Abstract to the page
+(as it appears on PubMed at http://www.pubmed.gov), where 8564542 is the PubMed ID number.
+-->
+{{ABSTRACT_PUBMED_8564542}}
 ==About this Structure==
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 [[Category: Hydrolase]]
 [[Category: O-glycosyl]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 12:44:18 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 20:45:18 2008''