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'''PYRUVATE KINASE COMPLEX WITH BIS MG-ATP-NA-OXALATE''' | '''PYRUVATE KINASE COMPLEX WITH BIS MG-ATP-NA-OXALATE''' | ||
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[[Category: Rayment, I.]] | [[Category: Rayment, I.]] | ||
[[Category: Reed, G H.]] | [[Category: Reed, G H.]] | ||
[[Category: | [[Category: Pyruvate kinase]] | ||
[[Category: | [[Category: Transferase]] | ||
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Revision as of 09:51, 2 May 2008
PYRUVATE KINASE COMPLEX WITH BIS MG-ATP-NA-OXALATE
OverviewOverview
Pyruvate kinase from rabbit muscle has been cocrystallized as a complex with MgIIATP, oxalate, Mg2+, and either K+ or Na+. Crystals with either Na+ or K+ belong to the space group P2(1)2(1)2(1), and the asymmetric units contain two tetramers. The structures were solved by molecular replacement and refined to 2.1 (K+) and 2.35 A (Na+) resolution. The structures of the Na+ and K+ complexes are virtually isomorphous. Each of the eight subunits within the asymmetric unit contains MgIIoxalate as a bidentate complex linked to the protein through coordination of Mg2+ to the carboxylates of Glu 271 and Asp 295. Six of the subunits also contain an alpha,beta,gamma-tridentate complex of MgIIATP, and the active-site cleft, located between domains A and B, is closed in these subunits. In the remaining two subunits MgIIATP is missing, and the active-site cleft is open. Closure of the active-site cleft in the fully liganded subunits includes a rotation of 41 degrees of the B domain relative to the A domain. alpha-Carbons of residues in the B domain undergo movements of up to 17.8 A (Lys 124) in the cleft closure. Lys 206, Arg 119, and Asp 177 from the B domain move several angstroms from their positions in the open conformation to contact the MgIIATP complex in the active site. The gamma-phosphate of ATP coordinates to both magnesium ions and to the monovalent cation, K+ or Na+. A Mg2+-coordinated oxygen from the MgIIoxalate complex lies 3.0 A from Pgamma of ATP, and this oxygen is positioned for an in-line attack on the phosphorus. The side chains of Lys 269 and Arg 119 are positioned to provide leaving-group activation in the forward and reverse directions. There is no obvious candidate for the acid/base catalyst near the 2-si face of the prospective enolate of the normal substrate. A functional group linked through solvent and side-chain hydroxyls may function in a proton relay.
About this StructureAbout this Structure
1A5U is a Single protein structure of sequence from Oryctolagus cuniculus. Full crystallographic information is available from OCA.
ReferenceReference
Structure of the bis(Mg2+)-ATP-oxalate complex of the rabbit muscle pyruvate kinase at 2.1 A resolution: ATP binding over a barrel., Larsen TM, Benning MM, Rayment I, Reed GH, Biochemistry. 1998 May 5;37(18):6247-55. PMID:9572839 Page seeded by OCA on Fri May 2 09:51:23 2008