1a69: Difference between revisions
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==Overview== | ==Overview== | ||
The ternary complex of purine nucleoside phosphorylase from E. coli with, formycin B and a sulphate or phosphate ion crystallized in the hexagonal, space group P6122 with unit cell dimensions a=123.11, c=241.22 A and three, monomers per asymmetric unit. The biologically active hexamer is formed, through 2-fold crystallographic symmetry, constituting a trimer of dimers., High-resolution X-ray diffraction data were collected using synchrotron, radiation (Daresbury, England). The crystal structure was determined by, molecular replacement and refined at 2.1 A resolution to an R-value of, 0.196.There is one active centre per monomer, composed of residues, belonging to two subunits of one dimer. The phosphate binding site is, strongly positively charged and consists of three arginine residues, ... | The ternary complex of purine nucleoside phosphorylase from E. coli with, formycin B and a sulphate or phosphate ion crystallized in the hexagonal, space group P6122 with unit cell dimensions a=123.11, c=241.22 A and three, monomers per asymmetric unit. The biologically active hexamer is formed, through 2-fold crystallographic symmetry, constituting a trimer of dimers., High-resolution X-ray diffraction data were collected using synchrotron, radiation (Daresbury, England). The crystal structure was determined by, molecular replacement and refined at 2.1 A resolution to an R-value of, 0.196.There is one active centre per monomer, composed of residues, belonging to two subunits of one dimer. The phosphate binding site is, strongly positively charged and consists of three arginine residues, (Arg24, Arg87 and Arg43 from a neighbouring subunit), Ser90 and Gly20. It, is occupied by a sulphate or phosphate anion, each oxygen atom of which, accepts at least two hydrogen bonds or salt-bridges. The sulphate or, phosphate anion is also in direct contact with the ribose moiety of, formycin B. The ribose binding site is composed of Ser90, Met180, Glu181, and His4, the latter belonging to the neighbouring subunit. The base, binding site is exposed to solvent, and the base is unspecifically bound, through a chain of water molecules and aromatic-aromatic interactions. In, all monomers the nucleosides are in the high syn conformation about the, glycosidic bonds with chi in the range 100 to 130 degrees. The, architecture of the active centre is in line with the known broad, specificity and the kinetic properties of E. coli PNP. | ||
==About this Structure== | ==About this Structure== | ||
1A69 is a | 1A69 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with SO4 and FMB as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Purine-nucleoside_phosphorylase Purine-nucleoside phosphorylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.1 2.4.2.1] Structure known Active Site: AVE. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1A69 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: transferase]] | [[Category: transferase]] | ||
''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 12:48:17 2007'' | ||
