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1eua

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{{STRUCTURE_1eua| PDB=1eua | SCENE= }}
{{STRUCTURE_1eua| PDB=1eua | SCENE= }}
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'''SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI'''
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===SCHIFF BASE INTERMEDIATE IN KDPG 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.
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(as it appears on PubMed at http://www.pubmed.gov), where 11274385 is the PubMed ID number.
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{{ABSTRACT_PUBMED_11274385}}
==About this Structure==
==About this Structure==
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[[Category: Carbinolamine]]
[[Category: Carbinolamine]]
[[Category: Trimer]]
[[Category: Trimer]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 01:59:49 2008''

Revision as of 22:59, 30 June 2008

Image:1eua.png

Template:STRUCTURE 1eua

SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI

Template:ABSTRACT PUBMED 11274385

About this Structure

1EUA is a Single protein structure of sequence from Escherichia coli. 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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