1a39: Difference between revisions
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==Overview== | ==Overview== | ||
Family 7 of the glycosyl hydrolases contains both endoglucanases and, cellobiohydrolases. In addition to their different catalytic activities on, crystalline substrates, the cellobiohydrolases differ from the, endoglucanases in their activity on longer soluble substrates, indicative, of a greater number of subsites on the enzyme. A double mutant (S37W, P39W) of the Humicola insolens endoglucanase I (EG I) has been constructed, in order to mimic aspects of the subsite structure of the corresponding, family 7 cellobiohydrolase, cellobiohydrolase-I (CBH I). The 3-D crystal, structure of the double mutant has been solved and refined to a, crystallographic R-factor of 0.17 at a resolution of 2.2 A (1 A = 0.1 nm)., The two mutant tryptophans are clearly visible in the electron density and, are ... | Family 7 of the glycosyl hydrolases contains both endoglucanases and, cellobiohydrolases. In addition to their different catalytic activities on, crystalline substrates, the cellobiohydrolases differ from the, endoglucanases in their activity on longer soluble substrates, indicative, of a greater number of subsites on the enzyme. A double mutant (S37W, P39W) of the Humicola insolens endoglucanase I (EG I) has been constructed, in order to mimic aspects of the subsite structure of the corresponding, family 7 cellobiohydrolase, cellobiohydrolase-I (CBH I). The 3-D crystal, structure of the double mutant has been solved and refined to a, crystallographic R-factor of 0.17 at a resolution of 2.2 A (1 A = 0.1 nm)., The two mutant tryptophans are clearly visible in the electron density and, are in the same orientation as those found in the substrate binding groove, of CBH I. In addition to the substitutions, the C-terminal amino acids, (399QELQ), disordered in the native enzyme structure, are clearly visible, and there are a small number of minor loop movements associated with, differences in crystal packing. Kinetic determinations show that the S37W, P39W mutant EG I has almost identical activity, compared to native EG I, on small soluble cellodextrins. On phosphoric acid swollen cellulose there, is a small (30%), but significant, decrease in the apparent KM indicating, that the double mutant may indeed exhibit stronger binding to longer, polymeric substrates. | ||
==About this Structure== | ==About this Structure== | ||
1A39 is a | 1A39 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Humicola_insolens Humicola insolens] with NAG as [http://en.wikipedia.org/wiki/ligand ligand]. 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] Structure known Active Sites: ACI and NUC. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1A39 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: hydrolase]] | [[Category: hydrolase]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 15:19:07 2007'' | ||
