1h19: Difference between revisions

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{{STRUCTURE_1h19|  PDB=1h19  |  SCENE=  }}  
{{STRUCTURE_1h19|  PDB=1h19  |  SCENE=  }}  


'''STRUCTURE OF [E271Q] LEUKOTRIENE A4 HYDROLASE'''
===STRUCTURE OF [E271Q] LEUKOTRIENE A4 HYDROLASE===




==Overview==
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Leukotriene A(4) hydrolase/aminopeptidase is a bifunctional zinc metalloenzyme that converts the fatty acid epoxide leukotriene A(4) into leukotriene B(4), a potent chemoattractant and immune-modulating lipid mediator. Recently, the structure of leukotriene A(4) hydrolase revealed that Glu-271, which belongs to a conserved GXMEN motif in the M1 family of zinc peptidases, and Gln-136 are located at the active site. Here we report that mutagenetic replacements of Glu-271, but not Gln-136, abrogate both catalytic activities of leukotriene A(4) hydrolase. Furthermore, the 2.1 A crystal structure of [E271Q]leukotriene A(4) hydrolase revealed minimal conformational changes that could not explain the loss of enzyme function. We propose that the carboxylate of Glu-271 participates in an acid-induced opening of the epoxide moiety of leukotriene A(4) and formation of a carbocation intermediate. Moreover, Glu-271 appears to act as an N-terminal recognition site and may potentially stabilize the transition-state during turnover of peptides, a property that most likely pertains to all members of the M1 family of zinc aminopeptidases. Hence, Glu-271 is a unique example of an amino acid, which has dual and separate functions in two different catalytic reactions, involving lipid and peptide substrates, respectively.
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{{ABSTRACT_PUBMED_11675384}}


==About this Structure==
==About this Structure==
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[[Category: Leukotriene biosynthesis]]
[[Category: Leukotriene biosynthesis]]
[[Category: Metalloprotease]]
[[Category: Metalloprotease]]
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Revision as of 03:27, 1 July 2008

File:1h19.png

Template:STRUCTURE 1h19

STRUCTURE OF [E271Q] LEUKOTRIENE A4 HYDROLASE

Template:ABSTRACT PUBMED 11675384

About this Structure

1H19 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Leukotriene A4 hydrolase/aminopeptidase. Glutamate 271 is a catalytic residue with specific roles in two distinct enzyme mechanisms., Rudberg PC, Tholander F, Thunnissen MM, Haeggstrom JZ, J Biol Chem. 2002 Jan 11;277(2):1398-404. Epub 2001 Oct 23. PMID:11675384

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