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PDBsum entry 1bk0
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B-lactam antibiotic
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PDB id
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1bk0
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References listed in PDB file
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Key reference
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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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Abstract
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The biosynthesis of penicillin and cephalosporin antibiotics in microorganisms
requires the formation of the bicyclic nucleus of penicillin. Isopenicillin N
synthase (IPNS), a non-haem iron-dependent oxidase, catalyses the reaction of a
tripeptide, delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV), and
dioxygen to form isopenicillin N and two water molecules. Mechanistic studies
suggest the reaction is initiated by ligation of the substrate thiolate to the
iron centre, and proceeds through an enzyme-bound monocyclic intermediate. Here
we report the crystal structure of IPNS complexed to ferrous iron and ACV,
determined to 1.3 A resolution. Based on the structure, we propose a mechanism
for penicillin formation that involves ligation of ACV to the iron centre,
creating a vacant iron coordination site into which dioxygen can bind.
Subsequently, iron-dioxygen and iron-oxo species remove the requisite hydrogens
from ACV without the direct assistance of protein residues. The crystal
structure of the complex with the dioxygen analogue, NO and ACV bound to the
active-site iron supports this hypothesis.
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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
reprinted
by permission from Macmillan Publishers Ltd:
Nature
(1997,
387,
827-830)
copyright 1997.
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Secondary reference #1
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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 #2
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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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