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1zah

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[[Image:1zah.gif|left|200px]]
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{{STRUCTURE_1zah| PDB=1zah | SCENE= }}
{{STRUCTURE_1zah| PDB=1zah | SCENE= }}
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'''Fructose-1,6-bisphosphate aldolase from rabbit muscle'''
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===Fructose-1,6-bisphosphate aldolase from rabbit muscle===
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==Overview==
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Crystal structures were determined to 1.8 A resolution of the glycolytic enzyme fructose-1,6-bis(phosphate) aldolase trapped in complex with its substrate and a competitive inhibitor, mannitol-1,6-bis(phosphate). The enzyme substrate complex corresponded to the postulated Schiff base intermediate and has reaction geometry consistent with incipient C3-C4 bond cleavage catalyzed Glu-187, which is adjacent by to the Schiff base forming Lys-229. Atom arrangement about the cleaved bond in the reaction intermediate mimics a pericyclic transition state occurring in nonenzymatic aldol condensations. Lys-146 hydrogen-bonds the substrate C4 hydroxyl and assists substrate cleavage by stabilizing the developing negative charge on the C4 hydroxyl during proton abstraction. Mannitol-1,6-bis(phosphate) forms a noncovalent complex in the active site whose binding geometry mimics the covalent carbinolamine precursor. Glu-187 hydrogen-bonds the C2 hydroxyl of the inhibitor in the enzyme complex, substantiating a proton transfer role by Glu-187 in catalyzing the conversion of the carbinolamine intermediate to Schiff base. Modeling of the acyclic substrate configuration into the active site shows Glu-187, in acid form, hydrogen-bonding both substrate C2 carbonyl and C4 hydroxyl, thereby aligning the substrate ketose for nucleophilic attack by Lys-229. The multifunctional role of Glu-187 epitomizes a canonical mechanistic feature conserved in Schiff base-forming aldolases catalyzing carbohydrate metabolism. Trapping of tagatose-1,6-bis(phosphate), a diastereoisomer of fructose 1,6-bis(phosphate), displayed stereospecific discrimination and reduced ketohexose binding specificity. Each ligand induces homologous conformational changes in two adjacent alpha-helical regions that promote phosphate binding in the active site.
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(as it appears on PubMed at http://www.pubmed.gov), where 15870069 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15870069}}
==About this Structure==
==About this Structure==
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[[Category: Sygusch, J.]]
[[Category: Sygusch, J.]]
[[Category: Aldolase]]
[[Category: Aldolase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 10:57:10 2008''

Revision as of 07:57, 28 July 2008

Image:1zah.png

Template:STRUCTURE 1zah

Fructose-1,6-bisphosphate aldolase from rabbit muscle

Template:ABSTRACT PUBMED 15870069

About this Structure

1ZAH is a Single protein structure of sequence from Oryctolagus cuniculus. Full crystallographic information is available from OCA.

Reference

High resolution reaction intermediates of rabbit muscle fructose-1,6-bisphosphate aldolase: substrate cleavage and induced fit., St-Jean M, Lafrance-Vanasse J, Liotard B, Sygusch J, J Biol Chem. 2005 Jul 22;280(29):27262-70. Epub 2005 May 3. PMID:15870069

Page seeded by OCA on Mon Jul 28 10:57:10 2008

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