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| {{STRUCTURE_1k7e| PDB=1k7e | SCENE= }} | | {{STRUCTURE_1k7e| PDB=1k7e | SCENE= }} |
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| '''CRYSTAL STRUCTURE OF WILD-TYPE TRYPTOPHAN SYNTHASE COMPLEXED WITH N-[1H-INDOL-3-YL-ACETYL]GLYCINE ACID'''
| | ===CRYSTAL STRUCTURE OF WILD-TYPE TRYPTOPHAN SYNTHASE COMPLEXED WITH N-[1H-INDOL-3-YL-ACETYL]GLYCINE ACID=== |
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| ==Overview==
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| Tryptophan synthase is a bifunctional alpha(2)beta(2) complex catalyzing the last two steps of l-tryptophan biosynthesis. The natural substrates of the alpha-subunit indole- 3-glycerolphosphate and glyceraldehyde-3-phosphate, and the substrate analogs indole-3-propanolphosphate and dl-alpha-glycerol-3-phosphate are allosteric effectors of the beta-subunit activity. It has been shown recently, that the indole-3-acetyl amino acids indole-3-acetylglycine and indole-3-acetyl-l-aspartic acid are both alpha-subunit inhibitors and beta-subunit allosteric effectors, whereas indole-3-acetyl-l-valine is only an alpha-subunit inhibitor (Marabotti, A., Cozzini, P., and Mozzarelli, A. (2000) Biochim. Biophys. Acta 1476, 287-299). The crystal structures of tryptophan synthase complexed with indole-3-acetylglycine and indole-3-acetyl-l-aspartic acid show that both ligands bind to the active site such that the carboxylate moiety is positioned similarly as the phosphate group of the natural substrates. As a consequence, the residues of the alpha-active site that interact with the ligands are the same as observed in the indole 3-glycerolphosphate-enzyme complex. Ligand binding leads to closure of loop alphaL6 of the alpha-subunit, a key structural element of intersubunit communication. This is in keeping with the allosteric role played by these compounds. The structure of the enzyme complex with indole-3-acetyl-l-valine is quite different. Due to the hydrophobic lateral chain, this molecule adopts a new orientation in the alpha-active site. In this case, closure of loop alphaL6 is no longer observed, in agreement with its functioning only as an inhibitor of the alpha-subunit reaction.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11756456}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11756456 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11756456}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Pyridoxal phosphate]] | | [[Category: Pyridoxal phosphate]] |
| [[Category: Tryptophan biosynthesis]] | | [[Category: Tryptophan biosynthesis]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:24:02 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 09:54:06 2008'' |
