1q2e
From Proteopedia
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'''CELLOBIOHYDROLASE CEL7A WITH LOOP DELETION 245-252 AND BOUND NON-HYDROLYSABLE CELLOTETRAOSE''' | '''CELLOBIOHYDROLASE CEL7A WITH LOOP DELETION 245-252 AND BOUND NON-HYDROLYSABLE CELLOTETRAOSE''' | ||
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[[Category: Jones, T A.]] | [[Category: Jones, T A.]] | ||
[[Category: Stahlberg, J.]] | [[Category: Stahlberg, J.]] | ||
| - | [[Category: | + | [[Category: Cellotetraose]] |
| - | [[Category: | + | [[Category: Cellulase]] |
| - | [[Category: | + | [[Category: Cellulose degradation]] |
| - | [[Category: | + | [[Category: Glycoprotein]] |
| - | [[Category: | + | [[Category: Glycosidase]] |
| - | [[Category: | + | [[Category: Glycosylated protein]] |
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Loop deletion]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:46:53 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 02:46, 3 May 2008
CELLOBIOHYDROLASE CEL7A WITH LOOP DELETION 245-252 AND BOUND NON-HYDROLYSABLE CELLOTETRAOSE
Overview
The exo-loop of Trichoderma reesei cellobiohydrolase Cel7A forms the roof of the active site tunnel at the catalytic centre. Mutants were designed to study the role of this loop in crystalline cellulose degradation. A hydrogen bond to substrate made by a tyrosine at the tip of the loop was removed by the Y247F mutation. The mobility of the loop was reduced by introducing a new disulphide bridge in the mutant D241C/D249C. The tip of the loop was deleted in mutant Delta(G245-Y252). No major structural disturbances were observed in the mutant enzymes, nor was the thermostability of the enzyme affected by the mutations.The Y247F mutation caused a slight k(cat) reduction on 4-nitrophenyl lactoside, but only a small effect on cellulose hydrolysis. Deletion of the tip of the loop increased both k(cat) and K(M) and gave reduced product inhibition. Increased activity was observed on amorphous cellulose, while only half the original activity remained on crystalline cellulose. Stabilisation of the exo-loop by the disulphide bridge enhanced the activity on both amorphous and crystalline cellulose. The ratio Glc(2)/(Glc(3)+Glc(1)) released from cellulose, which is indicative of processive action, was highest with Tr Cel7A wild-type enzyme and smallest with the deletion mutant on both substrates. Based on these data it seems that the exo-loop of Tr Cel7A has evolved to facilitate processive crystalline cellulose degradation, which does not require significant conformational changes of this loop.
About this Structure
1Q2E is a Single protein structure of sequence from Hypocrea jecorina. Full crystallographic information is available from OCA.
Reference
Engineering the exo-loop of Trichoderma reesei cellobiohydrolase, Cel7A. A comparison with Phanerochaete chrysosporium Cel7D., von Ossowski I, Stahlberg J, Koivula A, Piens K, Becker D, Boer H, Harle R, Harris M, Divne C, Mahdi S, Zhao Y, Driguez H, Claeyssens M, Sinnott ML, Teeri TT, J Mol Biol. 2003 Oct 31;333(4):817-29. PMID:14568538 Page seeded by OCA on Sat May 3 05:46:53 2008
