2al1

From Proteopedia

---

Revision as of 06:04, 21 November 2007

proteopedia linkproteopedia link

spinqualitylabelsall models 2al1, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure Analysis of Enolase Mg Subunit Complex at pH 8.0

Overview

Enolase is a dimeric enzyme that catalyzes the interconversion of, 2-phospho-D-glycerate and phosphoenolpyruvate. This reversible dehydration, is effected by general acid-base catalysis that involves, principally, Lys345 and Glu211 (numbering system of enolase 1 from yeast). The crystal, structure of the inactive E211Q enolase shows that the protein is properly, folded. However, K345 variants have, thus far, failed to crystallize. This, problem was solved by crystallization of an engineered heterodimer of, enolase. The heterodimer was composed of an inactive subunit that has a, K345A mutation and an active subunit that has N80D and N126D surface, mutations to facilitate ion-exchange chromatographic separation of the, three dimeric species. The structure of this heterodimeric variant, in, complex with substrate/product, was obtained at 1.85 A resolution. The, structure was compared to a new structure of wild-type enolase obtained, from crystals belonging to the same space group. Asymmetric dimers having, one subunit exhibiting two of the three active site loops in an open, conformation and the other in a conformation having all three loops closed, appear in both structures. The K345A subunit of the heterodimer is in the, loop-closed conformation; its Calpha carbon atoms closely match those of, the corresponding subunit of wild-type enolase (root-mean-squared, deviation of 0.23 A). The kcat and kcat/Km values of the heterodimer are, approximately half those of the N80D/N126D homodimer, which suggests that, the subunits in solution are kinetically independent. A comparison of, enolase structures obtained from crystals belonging to different space, groups suggests that asymmetric dimers can be a consequence of the, asymmetric positioning of the subunits within the crystal lattice.

About this Structure

2AL1 is a Single protein structure of sequence from Saccharomyces cerevisiae with MG, CL, K, PEP and 2PG as ligands. Active as Phosphopyruvate hydratase, with EC number 4.2.1.11 Full crystallographic information is available from OCA.

Reference

Structure and catalytic properties of an engineered heterodimer of enolase composed of one active and one inactive subunit., Sims PA, Menefee AL, Larsen TM, Mansoorabadi SO, Reed GH, J Mol Biol. 2006 Jan 20;355(3):422-31. Epub 2005 Nov 8. PMID:16309698

Page seeded by OCA on Wed Nov 21 08:11:51 2007