Sandbox Reserved 655: Difference between revisions
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== '''Beta-1,4-Endoglucanase''' == | == '''Beta-1,4-Endoglucanase''' == | ||
<Structure load=' | <Structure load='3vdh' size='500' frame='true' align='right' caption='Beta-1,4-Endoglucanase' scene='Insert optional scene name here' /> | ||
Cellulose is one of the main components of the plant cell wall, found predominantly in the xylem tissue which is further protected by hemicellulose and pectin. Cellulases are enzymes that catalyze the hydrolysis of cellulose and belong to a group of enzymes termed glycoside hydrolases (GHs). Several members of the GH family demonstrate a modular architecture composed of one or two catalytic modules connected to several kinds of accessory modules (Schubot et al., 2004). The accessory modules can be involved in numerous functions. For example, some cellulases contain carbohydrate-binding modules (CBMs), which enhance the association of the catalytic modules with insoluble carbohydrates. Cellulases have been characterized as endo or exo according to their mode of action on the substrate (Parsiegla et al., 2002). The endocellulases cleave the cellulose chain at arbitrary points, while exocellulases cleave at the terminus of a chain to start the degradation process.Beta-1,4-glycosidic bonds link together the beta-D-glucopyranose units of cellulose. Beta-1-4-endoglucanase enzymes produced chiefly by fungi | Cellulose is one of the main components of the plant cell wall, found predominantly in the xylem tissue which is further protected by hemicellulose and pectin. Cellulases are enzymes that catalyze the hydrolysis of cellulose and belong to a group of enzymes termed glycoside hydrolases (GHs). Several members of the GH family demonstrate a modular architecture composed of one or two catalytic modules connected to several kinds of accessory modules (Schubot et al., 2004). The accessory modules can be involved in numerous functions. For example, some cellulases contain carbohydrate-binding modules (CBMs), which enhance the association of the catalytic modules with insoluble carbohydrates. Cellulases have been characterized as endo or exo according to their mode of action on the substrate (Parsiegla et al., 2002). The endocellulases cleave the cellulose chain at arbitrary points, while exocellulases cleave at the terminus of a chain to start the degradation process. Beta-1,4-glycosidic bonds link together the beta-D-glucopyranose units of cellulose. Beta-1-4-endoglucanase enzymes, produced chiefly by fungi, bacteria and protozoans, specifically cleave the internal bonds of the cellulose chain (Kumar et al., 2008). | ||
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In the past 20 years, researchers have found that endoglucanases cannot break down polysaccharides efficiently without the help of non-catalytic carbohydrate-binding modules. Thus, endoglucanase is mostly found in the form of a complex that is made up of three separate domains. The main domain contains the large, globular catalytic domain which expresses the active site. A loop of the protein chain forms a tunnel that encloses the active site. This is attached at the O-glycosylated B block hinge region of the catalytic domain to the smaller, globular CBM at its C-terminal A block by a linker peptide made up of proline, serine, and threonine (Nimlos, et al., 2007). | In the past 20 years, researchers have found that endoglucanases cannot break down polysaccharides efficiently without the help of non-catalytic carbohydrate-binding modules. Thus, endoglucanase is mostly found in the form of a complex that is made up of three separate domains. The main domain contains the large, globular catalytic domain which expresses the active site. A loop of the protein chain forms a tunnel that encloses the active site. This is attached at the O-glycosylated B block hinge region of the catalytic domain to the smaller, globular CBM at its C-terminal A block by a linker peptide made up of proline, serine, and threonine (Nimlos, et al., 2007). | ||
The figure on the right shows the two domains of GDH. The orange represent the glutamate binding sites and the blue sites represent the domain involved in assembly of the hexamer. | The figure on the right shows the two domains of GDH. The orange represent the glutamate binding sites and the blue sites represent the domain involved in assembly of the hexamer. | ||
<scene name=' | <scene name='Sandbox_Reserved_655/Domains/1'>Domain</scene> | ||
[[Image:structure.jpeg]] | [[Image:structure.jpeg]] | ||
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<references/> | <references/> | ||
(1) | (1) F.D. Schubot, I.A. Kataeva, J. Chang, A.K. Shah, L.G. Ljungdahl, J.P. Rose, B.-C. Wang. Structural basis for the exocellulase activity of the cellobiohydrolase CbhA from Clostridium thermocellum Biochemistry, 43 (2004), pp. 1163–1170 | ||
(2) | (2) G. Parsiegla, C. Reverbel, C. Tardif, H. Driguez, R. Haser. Structures of mutants of cellulase Cel48F of Clostridium cellulotyticum in complex with long hemithiocellooligosaccharides give rise to a new view of the substrate pathway during processive action | ||
J. Mol. Biol., 375 (2008), pp. 499–510 | |||
(3) | (3) Kumar, R., Sing, S., Singh, O.V. 2008. Bioconversion of lignocellulosic biomass: biochemical and molecular perspectives. J Ind Microbiol Biotechnol. 35: 377-391. | ||
(4) Smith, Thomas J., and Peter E. Peterson. "The Structure of Bovine Glutamate Dehydrogenase Provides Insights into the Mechanism of Allostery." Structure 7.7 (1999): 769-782. Print. | (4) Smith, Thomas J., and Peter E. Peterson. "The Structure of Bovine Glutamate Dehydrogenase Provides Insights into the Mechanism of Allostery." Structure 7.7 (1999): 769-782. Print. | ||
