1afr
From Proteopedia
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STEAROYL-ACYL CARRIER PROTEIN DESATURASE FROM CASTOR SEEDS
Overview
The three-dimensional structure of recombinant homodimeric delta9, stearoyl-acyl carrier protein desaturase, the archetype of the soluble, plant fatty acid desaturases that convert saturated to unsaturated fatty, acids, has been determined by protein crystallographic methods to a, resolution of 2.4 angstroms. The structure was solved by a combination of, single isomorphous replacement, anomalous contribution from the iron atoms, to the native diffraction data and 6-fold non-crystallographic symmetry, averaging. The 363 amino acid monomer consists of a single domain of 11, alpha-helices. Nine of these form an antiparallel helix bundle. The enzyme, subunit contains a di-iron centre, with ligands from four of the, alpha-helices in the helix bundle. The iron ions are bound in a highly, symmetric environment, with one of the irons forming interactions with the, side chains of E196 and H232 and the second iron with the side chains of, E105 and H146. Two additional glutamic acid side chains, from E143 and, E229, are within coordination distance to both iron ions. A water molecule, is found within the second coordination sphere from the iron atoms. The, lack of electron density corresponding to a mu-oxo bridge, and the long, (4.2 angstroms) distance between the iron ions suggests that this probably, represents the diferrous form of the enzyme. A deep channel which probably, binds the fatty acid extends from the surface into the interior of the, enzyme. Modelling of the substrate, stearic acid, into this channel places, the delta9 carbon atom in the vicinity of one of the iron ions.
About this Structure
1AFR is a Single protein structure of sequence from Ricinus communis with FE2 as ligand. Active as [acyl-carrier-protein_desaturase Acyl-[acyl-carrier-protein] desaturase], with EC number 1.14.19.2 Full crystallographic information is available from OCA.
Reference
Crystal structure of delta9 stearoyl-acyl carrier protein desaturase from castor seed and its relationship to other di-iron proteins., Lindqvist Y, Huang W, Schneider G, Shanklin J, EMBO J. 1996 Aug 15;15(16):4081-92. PMID:8861937 [[Category: Acyl-[acyl-carrier-protein] desaturase]]
Page seeded by OCA on Tue Nov 20 10:49:11 2007
