1eua
From Proteopedia
(New page: 200px<br /><applet load="1eua" size="450" color="white" frame="true" align="right" spinBox="true" caption="1eua, resolution 1.95Å" /> '''SCHIFF BASE INTERMED...) |
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| - | [[Image:1eua.gif|left|200px]]<br /><applet load="1eua" size=" | + | [[Image:1eua.gif|left|200px]]<br /><applet load="1eua" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1eua, resolution 1.95Å" /> | caption="1eua, resolution 1.95Å" /> | ||
'''SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI'''<br /> | '''SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI'''<br /> | ||
==Overview== | ==Overview== | ||
| - | 2-Keto-3-deoxy-6-phosphogluconate (KDPG) aldolase catalyzes the reversible | + | 2-Keto-3-deoxy-6-phosphogluconate (KDPG) aldolase catalyzes the reversible cleavage of KDPG to pyruvate and glyceraldehyde-3-phosphate. The enzyme is a class I aldolase whose reaction mechanism involves formation of Schiff base intermediates between Lys-133 and a keto substrate. A covalent adduct was trapped by flash freezing KDPG aldolase crystals soaked with 10 mM pyruvate in acidic conditions at pH 4.6. Structure determination to 1.95-A resolution showed that pyruvate had undergone nucleophilic attack with Lys-133, forming a protonated carbinolamine intermediate, a functional Schiff base precursor, which was stabilized by hydrogen bonding with active site residues. Carbinolamine interaction with Glu-45 indicates general base catalysis of several rate steps. Stereospecific addition is ensured by aromatic interaction of Phe-135 with the pyruvate methyl group. In the native structure, Lys-133 donates all of its hydrogen bonds, indicating the presence of an epsilon-ammonium salt group. Nucleophilic activation is postulated to occur by proton transfer in the monoprotonated zwitterionic pair (Glu-45/Lys-133). Formation of the zwitterionic pair requires prior side chain rearrangement by protonated Lys-133 to displace a water molecule, hydrogen bonded to the zwitterionic residues. |
==About this Structure== | ==About this Structure== | ||
| - | 1EUA 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 ACT, SO4 and PYR as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/2-dehydro-3-deoxy-phosphogluconate_aldolase 2-dehydro-3-deoxy-phosphogluconate aldolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.2.14 4.1.2.14] Full crystallographic information is available from [http:// | + | 1EUA 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=ACT:'>ACT</scene>, <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=PYR:'>PYR</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/2-dehydro-3-deoxy-phosphogluconate_aldolase 2-dehydro-3-deoxy-phosphogluconate aldolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.2.14 4.1.2.14] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EUA OCA]. |
==Reference== | ==Reference== | ||
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[[Category: trimer]] | [[Category: trimer]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:31:36 2008'' |
Revision as of 10:31, 21 February 2008
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SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI
Overview
2-Keto-3-deoxy-6-phosphogluconate (KDPG) aldolase catalyzes the reversible cleavage of KDPG to pyruvate and glyceraldehyde-3-phosphate. The enzyme is a class I aldolase whose reaction mechanism involves formation of Schiff base intermediates between Lys-133 and a keto substrate. A covalent adduct was trapped by flash freezing KDPG aldolase crystals soaked with 10 mM pyruvate in acidic conditions at pH 4.6. Structure determination to 1.95-A resolution showed that pyruvate had undergone nucleophilic attack with Lys-133, forming a protonated carbinolamine intermediate, a functional Schiff base precursor, which was stabilized by hydrogen bonding with active site residues. Carbinolamine interaction with Glu-45 indicates general base catalysis of several rate steps. Stereospecific addition is ensured by aromatic interaction of Phe-135 with the pyruvate methyl group. In the native structure, Lys-133 donates all of its hydrogen bonds, indicating the presence of an epsilon-ammonium salt group. Nucleophilic activation is postulated to occur by proton transfer in the monoprotonated zwitterionic pair (Glu-45/Lys-133). Formation of the zwitterionic pair requires prior side chain rearrangement by protonated Lys-133 to displace a water molecule, hydrogen bonded to the zwitterionic residues.
About this Structure
1EUA is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as 2-dehydro-3-deoxy-phosphogluconate aldolase, with EC number 4.1.2.14 Full crystallographic information is available from OCA.
Reference
Covalent intermediate trapped in 2-keto-3-deoxy-6- phosphogluconate (KDPG) aldolase structure at 1.95-A resolution., Allard J, Grochulski P, Sygusch J, Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):3679-84. PMID:11274385
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