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1eua
From Proteopedia
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[[Image:1eua.gif|left|200px]] | [[Image:1eua.gif|left|200px]] | ||
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'''SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI''' | '''SCHIFF BASE INTERMEDIATE IN KDPG ALDOLASE FROM ESCHERICHIA COLI''' | ||
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[[Category: Grochulski, P.]] | [[Category: Grochulski, P.]] | ||
[[Category: Sygusch, J.]] | [[Category: Sygusch, J.]] | ||
| - | [[Category: | + | [[Category: Beta barrel]] |
| - | [[Category: | + | [[Category: Carbinolamine]] |
| - | [[Category: | + | [[Category: Trimer]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:31:24 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 12:31, 2 May 2008
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. 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 Page seeded by OCA on Fri May 2 15:31:24 2008
