2scu
From Proteopedia
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A DETAILED DESCRIPTION OF THE STRUCTURE OF SUCCINYL-COA SYNTHETASE FROM ESCHERICHIA COLI
Overview
Succinyl-CoA synthetase (SCS) carries out the substrate-level, phosphorylation of GDP or ADP in the citric acid cycle. A molecular model, of the enzyme from Escherichia coli, crystallized in the presence of CoA, has been refined against data collected to 2.3 A resolution. The crystals, are of space group P4322, having unit cell dimensions a=b=98.68 A, c=403.76 A and the data set includes the data measured from 23 crystals., E. coli SCS is an (alphabeta)2-tetramer; there are two copies of each, subunit in the asymmetric unit of the crystals. The crystal packing leaves, two choices for which pair of alphabeta-dimers form the physiologically, relevant tetramer. The copies of the alphabeta-dimer are similar, each, having one active site where the phosphorylated histidine residue and the, thiol group of CoA are found. CoA is bound in an extended conformation to, the nucleotide-binding motif in the N-terminal domain of the, alpha-subunit. The phosphoryl group of the phosphorylated histidine, residue is positioned at the amino termini of two alpha-helices, one from, the C-terminal domain of the alpha-subunit and the other from the, C-terminal domain of the beta-subunit. These two domains have similar, topologies, despite only 14 % sequence identity. By analogy to other, nucleotide-binding proteins, the binding site for the nucleotide may, reside in the N-terminal domain of the beta-subunit. If this is so, the, catalytic histidine residue would have to move about 35 A to react with, the nucleotide.
About this Structure
2SCU is a Protein complex structure of sequences from Escherichia coli with SO4 and COA as ligands. Active as Succinate--CoA ligase (ADP-forming), with EC number 6.2.1.5 Full crystallographic information is available from OCA.
Reference
A detailed structural description of Escherichia coli succinyl-CoA synthetase., Fraser ME, James MN, Bridger WA, Wolodko WT, J Mol Biol. 1999 Jan 29;285(4):1633-53. PMID:9917402
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