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| [[Image:1mac.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1mac| PDB=1mac | SCENE= }} | | {{STRUCTURE_1mac| PDB=1mac | SCENE= }} |
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| '''CRYSTAL STRUCTURE AND SITE-DIRECTED MUTAGENESIS OF BACILLUS MACERANS ENDO-1,3-1,4-BETA-GLUCANASE'''
| | ===CRYSTAL STRUCTURE AND SITE-DIRECTED MUTAGENESIS OF BACILLUS MACERANS ENDO-1,3-1,4-BETA-GLUCANASE=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_7852389}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 7852389 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_7852389}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hahn, M.]] | | [[Category: Hahn, M.]] |
| [[Category: Heinemann, U.]] | | [[Category: Heinemann, U.]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 00:49:21 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 23:33:17 2008'' |
