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| {{STRUCTURE_2z9w| PDB=2z9w | SCENE= }} | | {{STRUCTURE_2z9w| PDB=2z9w | SCENE= }} |
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| '''Crystal structure of pyridoxamine-pyruvate aminotransferase complexed with pyridoxal'''
| | ===Crystal structure of pyridoxamine-pyruvate aminotransferase complexed with pyridoxal=== |
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| ==Overview==
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| Pyridoxamine-pyruvate aminotransferase (PPAT; EC 2.6.1.30) is a pyridoxal 5'-phosphate-independent aminotransferase and catalyzes reversible transamination between pyridoxamine and pyruvate to form pyridoxal and L-alanine. The crystal structure of PPAT from Mesorhizobium loti has been solved in space group P4(3)2(1)2 and was refined to an R factor of 15.6% (R(free) = 20.6%) at 2.0 A resolution. In addition, the structures of PPAT in complexes with pyridoxamine, pyridoxal, and pyridoxyl-L-alanine have been refined to R factors of 15.6, 15.4, and 14.5% (R(free) = 18.6, 18.1, and 18.4%) at 1.7, 1.7, and 2.0 A resolution, respectively. PPAT is a homotetramer and each subunit is composed of a large N-terminal domain, consisting of seven beta-sheets and eight alpha-helices, and a smaller C-terminal domain, consisting of three beta-sheets and four alpha-helices. The substrate pyridoxal is bound through an aldimine linkage to Lys-197 in the active site. The alpha-carboxylate group of the substrate amino/keto acid is hydrogen-bonded to Arg-336 and Arg-345. The structures revealed that the bulky side chain of Glu-68 interfered with the binding of the phosphate moiety of pyridoxal 5'-phosphate and made PPAT specific to pyridoxal. The reaction mechanism of the enzyme is discussed based on the structures and kinetics results.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17989071}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17989071 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17989071}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Pyridoxamine]] | | [[Category: Pyridoxamine]] |
| [[Category: Pyruvate]] | | [[Category: Pyruvate]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jun 4 10:00:43 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 21:38:38 2008'' |
