1cb2
From Proteopedia
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| - | [[Image:1cb2.gif|left|200px]]<br /><applet load="1cb2" size=" | + | [[Image:1cb2.gif|left|200px]]<br /><applet load="1cb2" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1cb2, resolution 2.0Å" /> | caption="1cb2, resolution 2.0Å" /> | ||
'''CELLOBIOHYDROLASE II, CATALYTIC DOMAIN, MUTANT Y169F'''<br /> | '''CELLOBIOHYDROLASE II, CATALYTIC DOMAIN, MUTANT Y169F'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1CB2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Hypocrea_jecorina Hypocrea jecorina] with NAG and MAN as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cellulose_1,4-beta-cellobiosidase Cellulose 1,4-beta-cellobiosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.91 3.2.1.91] Known structural/functional Sites: <scene name='pdbsite=ST1:Catalytic Site Including Mutated TYR-> PHE'>ST1</scene> and <scene name='pdbsite=ST2:Catalytic Site Including Mutated TYR-> PHE'>ST2</scene>. Full crystallographic information is available from [http:// | + | 1CB2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Hypocrea_jecorina Hypocrea jecorina] with <scene name='pdbligand=NAG:'>NAG</scene> and <scene name='pdbligand=MAN:'>MAN</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cellulose_1,4-beta-cellobiosidase Cellulose 1,4-beta-cellobiosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.91 3.2.1.91] Known structural/functional Sites: <scene name='pdbsite=ST1:Catalytic+Site+Including+Mutated+TYR->+PHE'>ST1</scene> and <scene name='pdbsite=ST2:Catalytic+Site+Including+Mutated+TYR->+PHE'>ST2</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CB2 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: hydrolase (o-glycosyl)]] | [[Category: hydrolase (o-glycosyl)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb 3 09:34:27 2008'' |
Revision as of 07:34, 3 February 2008
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CELLOBIOHYDROLASE II, CATALYTIC DOMAIN, MUTANT Y169F
Overview
Trichoderma reesei cellobiohydrolase II (CBHII) is an exoglucanase, cleaving primarily cellobiose units from the non-reducing end of cellulose, chains. The beta-1,4 glycosidic bond is cleaved by acid catalysis with an, aspartic acid, D221, as the likely proton donor, and another aspartate, D175, probably ensuring its protonation and stabilizing charged reaction, intermediates. The catalytic base has not yet been identified, experimentally. The refined crystal structure of CBHII also shows a, tyrosine residue, Y169, located close enough to the scissile bond to be, involved in catalysis. The role of this residue has been studied by, introducing a mutation Y169F, and analysing the kinetic and binding, behavior of the mutated CBHII. The crystal structure of the mutated enzyme, was determined to 2.0 A resolution showing no changes when compared with, the structure of native CBHII. However, the association constants of the, mutant enzyme for cellobiose and cellotriose are increased threefold and, for 4-methylumbelliferyl cellobioside over 50-fold. The catalytic, constants towards cellotriose and cellotetraose are four times lower for, the mutant. These data suggest that Y169, on interacting with a glucose, ring entering the second subsite in a narrow tunnel, helps to distort the, glucose ring into a more reactive conformation. In addition, a change in, the pH activity profile was observed. This indicates that Y169 may have a, second role in the catalysis, namely to affect the protonation state of, the active site carboxylates, D175 and D221.
About this Structure
1CB2 is a Single protein structure of sequence from Hypocrea jecorina with and as ligands. Active as Cellulose 1,4-beta-cellobiosidase, with EC number 3.2.1.91 Known structural/functional Sites: and . Full crystallographic information is available from OCA.
Reference
The active site of Trichoderma reesei cellobiohydrolase II: the role of tyrosine 169., Koivula A, Reinikainen T, Ruohonen L, Valkeajarvi A, Claeyssens M, Teleman O, Kleywegt GJ, Szardenings M, Rouvinen J, Jones TA, Teeri TT, Protein Eng. 1996 Aug;9(8):691-9. PMID:8875646
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