1bk1
From Proteopedia
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| - | [[Image:1bk1. | + | [[Image:1bk1.jpg|left|200px]]<br /><applet load="1bk1" size="450" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1bk1" size="450" color="white" frame="true" align="right" spinBox="true" | + | |
caption="1bk1, resolution 2.0Å" /> | caption="1bk1, resolution 2.0Å" /> | ||
'''ENDO-1,4-BETA-XYLANASE C'''<br /> | '''ENDO-1,4-BETA-XYLANASE C'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1BK1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_kawachii Aspergillus kawachii]. Active as [http://en.wikipedia.org/wiki/Endo-1,4-beta-xylanase Endo-1,4-beta-xylanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.8 3.2.1.8] | + | 1BK1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_kawachii Aspergillus kawachii]. Active as [http://en.wikipedia.org/wiki/Endo-1,4-beta-xylanase Endo-1,4-beta-xylanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.8 3.2.1.8] Known structural/functional Site: <scene name='pdbsite=AS:GLU 79 And GLU 170 Refer To The Catalytic Acidic Residues'>AS</scene>. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1BK1 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: xylan degradation]] | [[Category: xylan degradation]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Dec 18 14:28:34 2007'' |
Revision as of 12:18, 18 December 2007
|
ENDO-1,4-BETA-XYLANASE C
Overview
Xylanase C from Aspergillus kawachii has an optimum pH of 2.0 and is, stable at pH 1.0. The crystal structure of xylanase C was determined at, 2.0 A resolution (R-factor = 19.4%). The overall structure was similar to, those of other family 11 xylanases. Asp37 and an acid-base catalyst, Glu170, are located at a hydrogen-bonding distance (2.8 A), as in other, xylanases with low pH optima. Asp37 of xylanase C was replaced with, asparagine and other residues by site-directed mutagenesis. Analyses of, the wild-type and mutant enzymes showed that Asp37 is important for high, enzyme activity at low pH. In the case of the asparagine mutant, the, optimum pH shifted to 5.0 and the maximum specific activity decreased to, about 15% of that of the wild-type enzyme. On structural comparison with, xylanases with higher pH optima, another striking feature of the xylanase, C structure was found; the enzyme has numerous acidic residues, concentrated on the surface (so-called 'Ser/Thr surface' in most family 11, xylanases). The relationship of the stability against extreme pH, conditions and high salt concentrations with the spatially biased, distribution of charged residues on the proteins is discussed.
About this Structure
1BK1 is a Single protein structure of sequence from Aspergillus kawachii. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Crystallographic and mutational analyses of an extremely acidophilic and acid-stable xylanase: biased distribution of acidic residues and importance of Asp37 for catalysis at low pH., Fushinobu S, Ito K, Konno M, Wakagi T, Matsuzawa H, Protein Eng. 1998 Dec;11(12):1121-8. PMID:9930661
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