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PDBsum entry 1afr
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Oxidoreductase
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PDB id
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1afr
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Crystal structure of delta9 stearoyl-Acyl carrier protein desaturase from castor seed and its relationship to other di-Iron proteins.
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Authors
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Y.Lindqvist,
W.Huang,
G.Schneider,
J.Shanklin.
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Ref.
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Embo J, 1996,
15,
4081-4092.
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PubMed id
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Abstract
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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.
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Secondary reference #1
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Title
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Preliminary crystallographic data for stearoyl-Acyl carrier protein desaturase from castor seed.
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Authors
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G.Schneider,
Y.Lindqvist,
J.Shanklin,
C.Somerville.
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Ref.
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J Mol Biol, 1992,
225,
561-564.
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PubMed id
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