4pga: Difference between revisions
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==Overview== | ==Overview== | ||
Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of, D- and L-isomers of glutamine and asparagine. X-ray quality type-1, crystals of PGA have been obtained from 2.0 M ammonium sulfate. The space, group is C222(1) with unit-cell dimensions a = 78.62, b = 135.80, and c =, 137.88 A. The tetrameric molecule is located on a crystallographic 2-fold, axis, and two subunits form the asymmetric portion of the unit cell. The, structure was solved by the molecular replacement method and refined at, 1.7 A resolution to an R = 19.9% with a good geometry of the model, G =, 0.05. The resultant electron density maps enabled us to resolve individual, constituent atoms of most residues and introduce minor revisions to the, amino acid sequence. The catalytic loop, Thr20-Gly40, is in ... | Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of, D- and L-isomers of glutamine and asparagine. X-ray quality type-1, crystals of PGA have been obtained from 2.0 M ammonium sulfate. The space, group is C222(1) with unit-cell dimensions a = 78.62, b = 135.80, and c =, 137.88 A. The tetrameric molecule is located on a crystallographic 2-fold, axis, and two subunits form the asymmetric portion of the unit cell. The, structure was solved by the molecular replacement method and refined at, 1.7 A resolution to an R = 19.9% with a good geometry of the model, G =, 0.05. The resultant electron density maps enabled us to resolve individual, constituent atoms of most residues and introduce minor revisions to the, amino acid sequence. The catalytic loop, Thr20-Gly40, is in the closed, conformation with excellent electron density in both subunits. A sulfate, ion and an ammonium ion are bound in the substrate binding site and, interect with the loop. This interaction appears to be responsible for the, observed closed conformation. New arguments supporting Thr20 as the, catalytic nucleophile in the asparaginase activity are proposed. | ||
==About this Structure== | ==About this Structure== | ||
4PGA is a | 4PGA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp._7a Pseudomonas sp. 7a] with SO4 and NH4 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glutamin-(asparagin-)ase Glutamin-(asparagin-)ase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.38 3.5.1.38] Structure known Active Sites: AS1 and AS2. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=4PGA OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: bacterial amidohydrolase]] | [[Category: bacterial amidohydrolase]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 12:51:05 2007'' | ||
