1xnc
From Proteopedia
(New page: 200px<br /><applet load="1xnc" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xnc, resolution 1.6Å" /> '''THERMOSTABILIZATION O...) |
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| - | [[Image:1xnc.gif|left|200px]]<br /><applet load="1xnc" size=" | + | [[Image:1xnc.gif|left|200px]]<br /><applet load="1xnc" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1xnc, resolution 1.6Å" /> | caption="1xnc, resolution 1.6Å" /> | ||
'''THERMOSTABILIZATION OF THE BACILLUS CIRCULANS XYLANASE, BY THE INTRODUCTION OF DISULFIDE BONDS'''<br /> | '''THERMOSTABILIZATION OF THE BACILLUS CIRCULANS XYLANASE, BY THE INTRODUCTION OF DISULFIDE BONDS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The thermostability of the 20 396 Da Bacillus circulans xylanase was | + | The thermostability of the 20 396 Da Bacillus circulans xylanase was increased by the introduction of both intra- and intermolecular disulfide bridges by site-directed mutagenesis. Based on the 3-D structure of the enzyme, sites were chosen where favourable geometry for a bridge existed; in one case, to obtain favourable geometry additional mutations around the cysteine sites were designed by computer modelling. The disulfide bonds introduced into the xylanase were mostly buried and, in the absence of protein denaturants, relatively insensitive to reduction by dithiothreitol. The mutant proteins were examined for residual enzymatic activity after various thermal treatments, and were assayed for enzymatic activity at elevated temperatures to assess their productivity. We have examined one of these mutants by X-ray crystallography. All of the disulfide bond designs tested increased the thermostability of the B. circulans xylanase, but not all enhanced the activity of the enzyme at elevated temperatures. |
==About this Structure== | ==About this Structure== | ||
| - | 1XNC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_circulans Bacillus circulans]. 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] Full crystallographic information is available from [http:// | + | 1XNC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_circulans Bacillus circulans]. 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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XNC OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Endo-1,4-beta-xylanase]] | [[Category: Endo-1,4-beta-xylanase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Campbell, R | + | [[Category: Campbell, R L.]] |
[[Category: glycosidase]] | [[Category: glycosidase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:56:38 2008'' |
Revision as of 13:56, 21 February 2008
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THERMOSTABILIZATION OF THE BACILLUS CIRCULANS XYLANASE, BY THE INTRODUCTION OF DISULFIDE BONDS
Overview
The thermostability of the 20 396 Da Bacillus circulans xylanase was increased by the introduction of both intra- and intermolecular disulfide bridges by site-directed mutagenesis. Based on the 3-D structure of the enzyme, sites were chosen where favourable geometry for a bridge existed; in one case, to obtain favourable geometry additional mutations around the cysteine sites were designed by computer modelling. The disulfide bonds introduced into the xylanase were mostly buried and, in the absence of protein denaturants, relatively insensitive to reduction by dithiothreitol. The mutant proteins were examined for residual enzymatic activity after various thermal treatments, and were assayed for enzymatic activity at elevated temperatures to assess their productivity. We have examined one of these mutants by X-ray crystallography. All of the disulfide bond designs tested increased the thermostability of the B. circulans xylanase, but not all enhanced the activity of the enzyme at elevated temperatures.
About this Structure
1XNC is a Single protein structure of sequence from Bacillus circulans. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Full crystallographic information is available from OCA.
Reference
Thermostabilization of the Bacillus circulans xylanase by the introduction of disulfide bonds., Wakarchuk WW, Sung WL, Campbell RL, Cunningham A, Watson DC, Yaguchi M, Protein Eng. 1994 Nov;7(11):1379-86. PMID:7700870
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