1chk
From Proteopedia
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==Overview== | ==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, . | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1CHK is a | + | 1CHK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_sp. Streptomyces sp.]. Structure known Active Site: CAT. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1CHK OCA]. |
==Reference== | ==Reference== | ||
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[[Category: o-glycosyl]] | [[Category: o-glycosyl]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 14:42:45 2007'' |
Revision as of 12:37, 5 November 2007
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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.
About this Structure
1CHK is a Single protein structure of sequence from Streptomyces sp.. Structure known Active Site: CAT. Full crystallographic information is available from OCA.
Reference
X-ray structure of an anti-fungal chitosanase from streptomyces N174., Marcotte EM, Monzingo AF, Ernst SR, Brzezinski R, Robertus JD, Nat Struct Biol. 1996 Feb;3(2):155-62. PMID:8564542
Page seeded by OCA on Mon Nov 5 14:42:45 2007
