From Proteopedia
(Difference between revisions)
proteopedia linkproteopedia link
|
|
| Line 1: |
Line 1: |
| - | [[Image:2quu.jpg|left|200px]] | + | {{Seed}} |
| | + | [[Image:2quu.png|left|200px]] |
| | | | |
| | <!-- | | <!-- |
| Line 9: |
Line 10: |
| | {{STRUCTURE_2quu| PDB=2quu | SCENE= }} | | {{STRUCTURE_2quu| PDB=2quu | SCENE= }} |
| | | | |
| - | '''Dihydroxyacetone phosphate Schiff base intermediate in mutant fructose-1,6-bisphosphate aldolase from rabbit muscle'''
| + | ===Dihydroxyacetone phosphate Schiff base intermediate in mutant fructose-1,6-bisphosphate aldolase from rabbit muscle=== |
| | | | |
| | | | |
| - | ==Overview==
| + | <!-- |
| - | Class I fructose-1,6-bisphosphate aldolases catalyze the interconversion between the enamine and iminium covalent enzymatic intermediates by stereospecific exchange of the pro(S) proton of the dihydroxyacetone-phosphate C3 carbon, an obligatory reaction step during substrate cleavage. To investigate the mechanism of stereospecific proton exchange, high resolution crystal structures of native and a mutant Lys(146) --> Met aldolase were solved in complex with dihydroxyacetone phosphate. The structural analysis revealed trapping of the enamine intermediate at Lys(229) in native aldolase. Mutation of conserved active site residue Lys(146) to Met drastically decreased activity and enabled trapping of the putative iminium intermediate in the crystal structure showing active site attachment by C-terminal residues 360-363. Attachment positions the conserved C-terminal Tyr(363) hydroxyl within 2.9A of the C3 carbon in the iminium in an orientation consistent with incipient re face proton transfer. We propose a catalytic mechanism by which the mobile C-terminal Tyr(363) is activated by the iminium phosphate via a structurally conserved water molecule to yield a transient phenate, whose developing negative charge is stabilized by a Lys(146) positive charge, and which abstracts the C3 pro(S) proton forming the enamine. An identical C-terminal binding mode observed in the presence of phosphate in the native structure corroborates Tyr(363) interaction with Lys(146) and is consistent with transient C terminus binding in the enamine. The absence of charge stabilization and of a mobile C-terminal catalyst explains the extraordinary stability of enamine intermediates in transaldolases.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17728250}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17728250 is the PubMed ID number. |
| | + | --> |
| | + | {{ABSTRACT_PUBMED_17728250}} |
| | | | |
| | ==About this Structure== | | ==About this Structure== |
| Line 36: |
Line 40: |
| | [[Category: Schiff base]] | | [[Category: Schiff base]] |
| | [[Category: Substrate]] | | [[Category: Substrate]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 15:43:48 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 23:48:25 2008'' |
Revision as of 20:48, 28 July 2008
Template:STRUCTURE 2quu
Dihydroxyacetone phosphate Schiff base intermediate in mutant fructose-1,6-bisphosphate aldolase from rabbit muscle
Template:ABSTRACT PUBMED 17728250
About this Structure
2QUU is a Single protein structure of sequence from Oryctolagus cuniculus. Full crystallographic information is available from OCA.
Reference
Stereospecific proton transfer by a mobile catalyst in mammalian fructose-1,6-bisphosphate aldolase., St-Jean M, Sygusch J, J Biol Chem. 2007 Oct 19;282(42):31028-37. Epub 2007 Aug 29. PMID:17728250
Page seeded by OCA on Mon Jul 28 23:48:25 2008
