1jyx
From Proteopedia
(New page: 200px<br /><applet load="1jyx" size="450" color="white" frame="true" align="right" spinBox="true" caption="1jyx, resolution 1.75Å" /> '''E. COLI (lacZ) BETA-...) |
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| - | [[Image:1jyx.jpg|left|200px]]<br /><applet load="1jyx" size=" | + | [[Image:1jyx.jpg|left|200px]]<br /><applet load="1jyx" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1jyx, resolution 1.75Å" /> | caption="1jyx, resolution 1.75Å" /> | ||
'''E. COLI (lacZ) BETA-GALACTOSIDASE IN COMPLEX WITH IPTG'''<br /> | '''E. COLI (lacZ) BETA-GALACTOSIDASE IN COMPLEX WITH IPTG'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The structures of a series of complexes designed to mimic intermediates | + | The structures of a series of complexes designed to mimic intermediates along the reaction coordinate for beta-galactosidase are presented. These complexes clarify and enhance previous proposals regarding the catalytic mechanism. The nucleophile, Glu537, is seen to covalently bind to the galactosyl moiety. Of the two potential acids, Mg(2+) and Glu461, the latter is in better position to directly assist in leaving group departure, suggesting that the metal ion acts in a secondary role. A sodium ion plays a part in substrate binding by directly ligating the galactosyl 6-hydroxyl. The proposed reaction coordinate involves the movement of the galactosyl moiety deep into the active site pocket. For those ligands that do bind deeply there is an associated conformational change in which residues within loop 794-804 move up to 10 A closer to the site of binding. In some cases this can be inhibited by the binding of additional ligands. The resulting restricted access to the intermediate helps to explain why allolactose, the natural inducer for the lac operon, is the preferred product of transglycosylation. |
==About this Structure== | ==About this Structure== | ||
| - | 1JYX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MG, NA, IPT and DMS as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-galactosidase Beta-galactosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.23 3.2.1.23] Full crystallographic information is available from [http:// | + | 1JYX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=NA:'>NA</scene>, <scene name='pdbligand=IPT:'>IPT</scene> and <scene name='pdbligand=DMS:'>DMS</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-galactosidase Beta-galactosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.23 3.2.1.23] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1JYX OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Juers, D | + | [[Category: Juers, D H.]] |
| - | [[Category: Matthews, B | + | [[Category: Matthews, B W.]] |
[[Category: DMS]] | [[Category: DMS]] | ||
[[Category: IPT]] | [[Category: IPT]] | ||
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[[Category: tim barrel (alpha/beta barrel)]] | [[Category: tim barrel (alpha/beta barrel)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:28:15 2008'' |
Revision as of 11:28, 21 February 2008
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E. COLI (lacZ) BETA-GALACTOSIDASE IN COMPLEX WITH IPTG
Overview
The structures of a series of complexes designed to mimic intermediates along the reaction coordinate for beta-galactosidase are presented. These complexes clarify and enhance previous proposals regarding the catalytic mechanism. The nucleophile, Glu537, is seen to covalently bind to the galactosyl moiety. Of the two potential acids, Mg(2+) and Glu461, the latter is in better position to directly assist in leaving group departure, suggesting that the metal ion acts in a secondary role. A sodium ion plays a part in substrate binding by directly ligating the galactosyl 6-hydroxyl. The proposed reaction coordinate involves the movement of the galactosyl moiety deep into the active site pocket. For those ligands that do bind deeply there is an associated conformational change in which residues within loop 794-804 move up to 10 A closer to the site of binding. In some cases this can be inhibited by the binding of additional ligands. The resulting restricted access to the intermediate helps to explain why allolactose, the natural inducer for the lac operon, is the preferred product of transglycosylation.
About this Structure
1JYX is a Single protein structure of sequence from Escherichia coli with , , and as ligands. Active as Beta-galactosidase, with EC number 3.2.1.23 Full crystallographic information is available from OCA.
Reference
A structural view of the action of Escherichia coli (lacZ) beta-galactosidase., Juers DH, Heightman TD, Vasella A, McCarter JD, Mackenzie L, Withers SG, Matthews BW, Biochemistry. 2001 Dec 11;40(49):14781-94. PMID:11732897
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