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1cem
From Proteopedia
(New page: 200px<br /><applet load="1cem" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cem, resolution 1.65Å" /> '''ENDOGLUCANASE A (CEL...) |
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| - | [[Image:1cem.jpg|left|200px]]<br /><applet load="1cem" size=" | + | [[Image:1cem.jpg|left|200px]]<br /><applet load="1cem" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1cem, resolution 1.65Å" /> | caption="1cem, resolution 1.65Å" /> | ||
'''ENDOGLUCANASE A (CELA) CATALYTIC CORE, RESIDUES 33-395'''<br /> | '''ENDOGLUCANASE A (CELA) CATALYTIC CORE, RESIDUES 33-395'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND. Cellulases, which catalyze the hydrolysis of glycosidic bonds | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1CEM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_thermocellum Clostridium thermocellum]. Active as [http://en.wikipedia.org/wiki/Cellulase Cellulase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.4 3.2.1.4] Full crystallographic information is available from [http:// | + | 1CEM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_thermocellum Clostridium thermocellum]. Active as [http://en.wikipedia.org/wiki/Cellulase Cellulase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.4 3.2.1.4] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CEM OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Clostridium thermocellum]] | [[Category: Clostridium thermocellum]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Alzari, P | + | [[Category: Alzari, P M.]] |
[[Category: cellulase]] | [[Category: cellulase]] | ||
[[Category: clostridium thermocellum]] | [[Category: clostridium thermocellum]] | ||
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[[Category: glycosyltransferase]] | [[Category: glycosyltransferase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:05:16 2008'' |
Revision as of 10:05, 21 February 2008
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ENDOGLUCANASE A (CELA) CATALYTIC CORE, RESIDUES 33-395
Overview
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.
About this Structure
1CEM is a Single protein structure of sequence from Clostridium thermocellum. Active as Cellulase, with EC number 3.2.1.4 Full crystallographic information is available from OCA.
Reference
The crystal structure of endoglucanase CelA, a family 8 glycosyl hydrolase from Clostridium thermocellum., Alzari PM, Souchon H, Dominguez R, Structure. 1996 Mar 15;4(3):265-75. PMID:8805535
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