1xpy: Difference between revisions

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[[Image:1xpy.gif|left|200px]]
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{{STRUCTURE_1xpy|  PDB=1xpy  |  SCENE=  }}  
{{STRUCTURE_1xpy|  PDB=1xpy  |  SCENE=  }}  


'''Structural Basis for Catalytic Racemization and Substrate Specificity of an N-Acylamino Acid Racemase Homologue from Deinococcus radiodurans'''
===Structural Basis for Catalytic Racemization and Substrate Specificity of an N-Acylamino Acid Racemase Homologue from Deinococcus radiodurans===




==Overview==
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N-acylamino acid racemase (NAAAR) catalyzes the racemization of N-acylamino acids and can be used in concert with an aminoacylase to produce enantiopure alpha-amino acids, a process that has potential industrial applications. Here we have cloned and characterized an NAAAR homologue from a radiation-resistant ancient bacterium, Deinococcus radiodurans. The expressed NAAAR racemized various substrates at an optimal temperature of 60 degrees C and had Km values of 24.8 mM and 12.3 mM for N-acetyl-D-methionine and N-acetyl-L-methionine, respectively. The crystal structure of NAAAR was solved to 1.3 A resolution using multiwavelength anomalous dispersion (MAD) methods. The structure consists of a homooctamer in which each subunit has an architecture characteristic of enolases with a capping domain and a (beta/alpha)7 beta barrel domain. The NAAAR.Mg2+ and NAAAR.N-acetyl-L-glutamine.Mg2+ structures were also determined, allowing us to define the Lys170-Asp195-Glu220-Asp245-Lys269 framework for catalyzing 1,1-proton exchange of N-acylamino acids. Four subsites enclosing the substrate are identified: catalytic site, metal-binding site, side-chain-binding region, and a flexible lid region. The high conservation of catalytic and metal-binding sites in different enolases reflects the essentiality of a common catalytic platform, allowing these enzymes to robustly abstract alpha-protons of various carboxylate substrates efficiently. The other subsites involved in substrate recognition are less conserved, suggesting that divergent evolution has led to functionally distinct enzymes.
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{{ABSTRACT_PUBMED_15313614}}


==About this Structure==
==About this Structure==
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[[Category: Wu, C L.]]
[[Category: Wu, C L.]]
[[Category: Racemase]]
[[Category: Racemase]]
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Revision as of 06:02, 28 July 2008

File:1xpy.png

Template:STRUCTURE 1xpy

Structural Basis for Catalytic Racemization and Substrate Specificity of an N-Acylamino Acid Racemase Homologue from Deinococcus radioduransStructural Basis for Catalytic Racemization and Substrate Specificity of an N-Acylamino Acid Racemase Homologue from Deinococcus radiodurans

Template:ABSTRACT PUBMED 15313614

About this StructureAbout this Structure

1XPY is a Single protein structure of sequence from Deinococcus radiodurans. Full crystallographic information is available from OCA.

ReferenceReference

Structural basis for catalytic racemization and substrate specificity of an N-acylamino acid racemase homologue from Deinococcus radiodurans., Wang WC, Chiu WC, Hsu SK, Wu CL, Chen CY, Liu JS, Hsu WH, J Mol Biol. 2004 Sep 3;342(1):155-69. PMID:15313614

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