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| [[Image:1cem.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1cem| PDB=1cem | SCENE= }} | | {{STRUCTURE_1cem| PDB=1cem | SCENE= }} |
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| '''ENDOGLUCANASE A (CELA) CATALYTIC CORE, RESIDUES 33-395'''
| | ===ENDOGLUCANASE A (CELA) CATALYTIC CORE, RESIDUES 33-395=== |
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| ==Overview==
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| BACKGROUND. Cellulases, which catalyze the hydrolysis of glycosidic bonds in cellulose, can be classified into several different protein families. Endoglucanase CelA is a member of glycosyl hydrolase family 8, a family for which no structural information was previously available. RESULTS. The crystal structure of CelA was determined by multiple isomorphous replacement and refined to 1.65 A resolution. The protein folds into a regular (alpha/alpha)6 barrel formed by six inner and six outer alpha helices. Cello-oligosaccharides bind to an acidic cleft containing at least five D-glucosyl-binding subsites (A-E) such that the scissile glycosidic linkage lies between subsites C and D. The strictly conserved residue Glu95, which occupies the center of the substrate-binding cleft and is hydrogen bonded to the glycosidic oxygen, has been assigned the catalytic role of proton donor. CONCLUSIONS. The present analysis provides a basis for modeling homologous family 8 cellulases. The architecture of the active-site cleft, presenting at least five glucosyl-binding subsites, explains why family 8 cellulases cleave cello-oligosaccharide polymers that are at least five D-glycosyl subunits long. Furthermore, the structure of CelA allows comparison with (alpha/alpha)6 barrel glycosidases that are not related in sequence, suggesting a possible, albeit distant, evolutionary relationship between different families of glycosyl hydrolases.
| | The line below this paragraph, {{ABSTRACT_PUBMED_8805535}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 8805535 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_8805535}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Glycosyl hydrolase]] | | [[Category: Glycosyl hydrolase]] |
| [[Category: Glycosyltransferase]] | | [[Category: Glycosyltransferase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:38:56 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 20:38:31 2008'' |
