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| {{STRUCTURE_1eun| PDB=1eun | SCENE= }} | | {{STRUCTURE_1eun| PDB=1eun | SCENE= }} |
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| '''STRUCTURE OF 2-KETO-3-DEOXY-6-PHOSPHOGLUCONATE ALDOLASE FROM ESCHERICHIA COLI'''
| | ===STRUCTURE OF 2-KETO-3-DEOXY-6-PHOSPHOGLUCONATE ALDOLASE FROM ESCHERICHIA COLI=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11274385}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11274385 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11274385}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Sulfate]] | | [[Category: Sulfate]] |
| [[Category: Trimer]] | | [[Category: Trimer]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:32:05 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 02:01:27 2008'' |
