1kd0
From Proteopedia
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'''Crystal Structure of beta-methylaspartase from Clostridium tetanomorphum. Apo-structure.''' | '''Crystal Structure of beta-methylaspartase from Clostridium tetanomorphum. Apo-structure.''' | ||
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[[Category: Gani, D.]] | [[Category: Gani, D.]] | ||
[[Category: Naismith, J H.]] | [[Category: Naismith, J H.]] | ||
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Revision as of 19:35, 2 May 2008
Crystal Structure of beta-methylaspartase from Clostridium tetanomorphum. Apo-structure.
Overview
Methylaspartate ammonia-lyase (3-methylaspartase, MAL; EC ) catalyzes the reversible anti elimination of ammonia from L-threo-(2S,3S)-3-methylaspartic acid to give mesaconic acid. This reaction lies on the main catabolic pathway for glutamate in Clostridium tetanomorphum. MAL requires monovalent and divalent cation cofactors for full catalytic activity. The enzyme has attracted interest because of its potential use as a biocatalyst. The structure of C. tetanomorphum MAL has been solved to 1.9-A resolution by the single-wavelength anomalous diffraction method. A divalent metal ion complex of the protein has also been determined. MAL is a homodimer with each monomer consisting of two domains. One is an alpha/beta-barrel, and the other smaller domain is mainly beta-strands. The smaller domain partially occludes the C terminus of the barrel and forms a large cleft. The structure identifies MAL as belonging to the enolase superfamily of enzymes. The metal ion site is located in a large cleft between the domains. Potential active site residues have been identified based on a combination of their proximity to a metal ion site, molecular modeling, and sequence homology. In common with all members of the enolase superfamily, the carboxylic acid of the substrate is co-ordinated by the metal ions, and a proton adjacent to a carboxylic acid group of the substrate is abstracted by a base. In MAL, it appears that Lys(331) removes the alpha-proton of methylaspartic acid. This motif is the defining mechanistic characteristic of the enolase superfamily of which all have a common fold. The degree of structural conservation is remarkable given only four residues are absolutely conserved.
About this Structure
1KD0 is a Single protein structure of sequence from Clostridium tetanomorphum. Full crystallographic information is available from OCA.
Reference
The structure of 3-methylaspartase from Clostridium tetanomorphum functions via the common enolase chemical step., Asuncion M, Blankenfeldt W, Barlow JN, Gani D, Naismith JH, J Biol Chem. 2002 Mar 8;277(10):8306-11. Epub 2001 Dec 17. PMID:11748244 Page seeded by OCA on Fri May 2 22:35:28 2008