1mac
From Proteopedia
(New page: 200px<br /><applet load="1mac" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mac, resolution 2.3Å" /> '''CRYSTAL STRUCTURE AND...) |
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| - | [[Image:1mac.jpg|left|200px]]<br /><applet load="1mac" size=" | + | [[Image:1mac.jpg|left|200px]]<br /><applet load="1mac" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1mac, resolution 2.3Å" /> | caption="1mac, resolution 2.3Å" /> | ||
'''CRYSTAL STRUCTURE AND SITE-DIRECTED MUTAGENESIS OF BACILLUS MACERANS ENDO-1,3-1,4-BETA-GLUCANASE'''<br /> | '''CRYSTAL STRUCTURE AND SITE-DIRECTED MUTAGENESIS OF BACILLUS MACERANS ENDO-1,3-1,4-BETA-GLUCANASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | In beta-glucans those beta-1,4 glycosidic bonds which are adjacent to | + | In beta-glucans those beta-1,4 glycosidic bonds which are adjacent to beta-1,3 bonds are cleaved by endo-1,3-1,4-beta-glucanases (beta-glucanases). Here, the relationship between structure and activity of the beta-glucanase of Bacillus macerans is studied by x-ray crystallography and site-directed mutagenesis of active site residues. Crystal structure analysis at 2.3-A resolution reveals a jelly-roll protein structure with a deep active site channel harboring the amino acid residues Trp101, Glu103, Asp105, and Glu107 as in the hybrid Bacillus beta-glucanase H(A16-M) (Keitel, T., Simon, O., Borriss, R., and Heinemann, U. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 5287-5291). Different mutant proteins with substitutions in these residues are generated by site-directed mutagenesis, isolated, and characterized. Compared with the wild-type enzyme their activity is reduced to less than 1%. Several mutants with isosteric substitutions in Glu103 and Glu107 are completely inactive, suggesting a direct role of these residues in glycosyl bond hydrolysis. The kinetic properties of mutant beta-glucanases and the crystal structure of the wild-type enzyme are consistent with a mechanism where Glu103 and Glu107 are the catalytic amino acid residues responsible for cleavage of the beta-1,4 glycosidic bond within the substrate molecule. |
==About this Structure== | ==About this Structure== | ||
| - | 1MAC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Paenibacillus_macerans Paenibacillus macerans] with CA as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Licheninase Licheninase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.73 3.2.1.73] Full crystallographic information is available from [http:// | + | 1MAC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Paenibacillus_macerans Paenibacillus macerans] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Licheninase Licheninase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.73 3.2.1.73] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MAC OCA]. |
==Reference== | ==Reference== | ||
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[[Category: hydrolase (glucanase)]] | [[Category: hydrolase (glucanase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:53:14 2008'' |
Revision as of 11:53, 21 February 2008
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CRYSTAL STRUCTURE AND SITE-DIRECTED MUTAGENESIS OF BACILLUS MACERANS ENDO-1,3-1,4-BETA-GLUCANASE
Overview
In beta-glucans those beta-1,4 glycosidic bonds which are adjacent to beta-1,3 bonds are cleaved by endo-1,3-1,4-beta-glucanases (beta-glucanases). Here, the relationship between structure and activity of the beta-glucanase of Bacillus macerans is studied by x-ray crystallography and site-directed mutagenesis of active site residues. Crystal structure analysis at 2.3-A resolution reveals a jelly-roll protein structure with a deep active site channel harboring the amino acid residues Trp101, Glu103, Asp105, and Glu107 as in the hybrid Bacillus beta-glucanase H(A16-M) (Keitel, T., Simon, O., Borriss, R., and Heinemann, U. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 5287-5291). Different mutant proteins with substitutions in these residues are generated by site-directed mutagenesis, isolated, and characterized. Compared with the wild-type enzyme their activity is reduced to less than 1%. Several mutants with isosteric substitutions in Glu103 and Glu107 are completely inactive, suggesting a direct role of these residues in glycosyl bond hydrolysis. The kinetic properties of mutant beta-glucanases and the crystal structure of the wild-type enzyme are consistent with a mechanism where Glu103 and Glu107 are the catalytic amino acid residues responsible for cleavage of the beta-1,4 glycosidic bond within the substrate molecule.
About this Structure
1MAC is a Single protein structure of sequence from Paenibacillus macerans with as ligand. Active as Licheninase, with EC number 3.2.1.73 Full crystallographic information is available from OCA.
Reference
Crystal structure and site-directed mutagenesis of Bacillus macerans endo-1,3-1,4-beta-glucanase., Hahn M, Olsen O, Politz O, Borriss R, Heinemann U, J Biol Chem. 1995 Feb 17;270(7):3081-8. PMID:7852389
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