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PDBsum entry 1qjf
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B-lactam antibiotic
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PDB id
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1qjf
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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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The reaction cycle of isopenicillin n synthase observed by X-Ray diffraction.
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Authors
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N.I.Burzlaff,
P.J.Rutledge,
I.J.Clifton,
C.M.Hensgens,
M.Pickford,
R.M.Adlington,
P.L.Roach,
J.E.Baldwin.
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Ref.
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Nature, 1999,
401,
721-724.
[DOI no: ]
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PubMed id
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Abstract
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Isopenicillin N synthase (IPNS), a non-haem iron-dependent oxidase, catalyses
the biosynthesis of isopenicillin N (IPN), the precursor of all penicillins and
cephalosporins. The key steps in this reaction are the two
iron-dioxygen-mediated ring closures of the tripeptide
delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV). It has been proposed
that the four-membered beta-lactam ring forms initially, associated with a
highly oxidized iron(iv)-oxo (ferryl) moiety, which subsequently mediates
closure of the five-membered thiazolidine ring. Here we describe observation of
the IPNS reaction in crystals by X-ray crystallography. IPNS Fe2+ substrate
crystals were grown anaerobically, exposed to high pressures of oxygen to
promote reaction and frozen, and their structures were elucidated by X-ray
diffraction. Using the natural substrate ACV, this resulted in the IPNS x Fe2+ x
IPN product complex. With the substrate analogue,
delta-(L-alpha-aminoadipoyl)-L-cysteinyl-L-S-methylcysteine (ACmC) in the
crystal, the reaction cycle was interrupted at the monocyclic stage. These mono-
and bicyclic structures support our hypothesis of a two-stage reaction sequence
leading to penicillin. Furthermore, the formation of a monocyclic sulphoxide
product from ACmC is most simply explained by the interception of a high-valency
iron-oxo species.
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Figure 2.
Figure 2 Proposed mechanisms for the oxidation of ACV and
ACmC to bicyclic and monocyclic products, respectively. See text
for details of compounds 1-6. AA, L-  -(
 -aminoadipoyl).
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Figure 3.
Figure 3 Stereo views of the two substrates and two products
overlaid. The key regions that participate in the reaction and
the iron atom (orange) are shown; the aminoadipoyl side chain,
which does not move significantly, is omitted for clarity. Shown
are ACV (white), IPN (yellow), ACmC (blue) and its monocyclic
sulphoxide product (pink). Figures were prepared using the
programs MOLSCRIPT20 and Raster3D (ref. 21).
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nature
(1999,
401,
721-724)
copyright 1999.
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Secondary reference #1
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Title
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Structure of isopenicillin n synthase complexed with substrate and the mechanism of penicillin formation.
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Authors
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P.L.Roach,
I.J.Clifton,
C.M.Hensgens,
N.Shibata,
C.J.Schofield,
J.Hajdu,
J.E.Baldwin.
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Ref.
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Nature, 1997,
387,
827-830.
[DOI no: ]
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PubMed id
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Figure 2.
Figure 2 Mechanism for isopenicillin N formation and the
formation of the Fe: ACV: NO:. sp;IPNS complex.
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Figure 3.
Figure 3 Comparison of the structures of Mn: IPNS (a) and
Fe(II): ACV: IPNS (. b) from the same orientation. The
jelly-roll motif is in green, the C-terminal region (residues
313-331) cyan, the active-site metal ion (manganese in a, iron
in b) orange, the key substrate-binding residues (His 214, His
270, Asp 216, Arg 87, Arg 279, Tyr 189 and Ser 281) magenta, and
the ACV yellow.
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The above figures are
reproduced from the cited reference
with permission from Macmillan Publishers Ltd
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Secondary reference #2
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Title
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Crystal structure of isopenicillin n synthase is the first from a new structural family of enzymes.
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Authors
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P.L.Roach,
I.J.Clifton,
V.Fülöp,
K.Harlos,
G.J.Barton,
J.Hajdu,
I.Andersson,
C.J.Schofield,
J.E.Baldwin.
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Ref.
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Nature, 1995,
375,
700-704.
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PubMed id
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Secondary reference #3
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Title
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Crystallization and preliminary X-Ray diffraction studies on recombinant isopenicillin n synthase from aspergillus nidulans.
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Authors
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P.L.Roach,
C.J.Schofield,
J.E.Baldwin,
I.J.Clifton,
J.Hajdu.
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Ref.
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Protein Sci, 1995,
4,
1007-1009.
[DOI no: ]
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PubMed id
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Figure 1.
Fig. 1. SnthesisfisopencillinNfromACVbyisopenicillinNsynthase.
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Figure 2.
G.E Lee and G.L. Hazelbauer
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The above figures are
reproduced from the cited reference
which is an Open Access publication published by the Protein Society
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