1tdj

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=PLP:PYRIDOXAL-5-PHOSPHATE'>PLP</scene></td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Threonine_ammonia-lyase Threonine ammonia-lyase], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.3.1.19 4.3.1.19] </span></td></tr>

[[https://www.uniprot.org/uniprot/ILVA_ECOLI ILVA_ECOLI]] Catalyzes the anaerobic formation of alpha-ketobutyrate and ammonia from threonine in a two-step reaction. The first step involved a dehydration of threonine and a production of enamine intermediates (aminocrotonate), which tautomerizes to its imine form (iminobutyrate). Both intermediates are unstable and short-lived. The second step is the nonenzymatic hydrolysis of the enamine/imine intermediates to form 2-ketobutyrate and free ammonia. In the low water environment of the cell, the second step is accelerated by RidA.<ref>PMID:13405870</ref>

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== Publication Abstract from PubMed ==

BACKGROUND: Feedback inhibition of biosynthetic threonine deaminase (TD) from Escherichia coli provided one of the earliest examples of protein-based metabolic regulation. Isoleucine, the pathway end-product, and valine, the product of a parallel pathway, serve as allosteric inhibitor and activator, respectively. This enzyme is thus a useful model system for studying the structural basis of allosteric control mechanisms. RESULTS: We report the crystal structure of TD at 2.8 A resolution. The tetramer has 222 symmetry, with C-terminal regulatory domains projecting out from a core of catalytic PLP-containing N-terminal domains. The subunits, and especially the regulatory domains, associate extensively to form dimers, which associate less extensively to form the tetramer. Within the dimer, each monomer twists approximately 150 degrees around a thin neck between the domains to place its catalytic domain adjacent to the regulatory domain of the other subunit. CONCLUSIONS: The structure of TD and its comparison with related structures and other data lead to the tentative identification of the regulatory binding site and revealed several implications for the allosteric mechanism. This work prepares the way for detailed structure/function studies of the complex allosteric behaviour of this enzyme.

Structure and control of pyridoxal phosphate dependent allosteric threonine deaminase.,Gallagher DT, Gilliland GL, Xiao G, Zondlo J, Fisher KE, Chinchilla D, Eisenstein E Structure. 1998 Apr 15;6(4):465-75. PMID:9562556<ref>PMID:9562556</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1tdj" style="background-color:#fffaf0;"></div>

[[Category: Eisenstein, E]]

[[Category: Gallagher, D T]]

[[Category: Gilliland, G L]]

[[Category: Xiao, G]]

[[Category: Tetramer]]