1qjf
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Isopenicillin N synthase (IPNS), a non-haem iron-dependent oxidase, catalyses the biosynthesis of isopenicillin N (IPN), the precursor of all | + | 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. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Emericella nidulans]] | [[Category: Emericella nidulans]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Adlington, R | + | [[Category: Adlington, R M.]] |
| - | [[Category: Baldwin, J | + | [[Category: Baldwin, J E.]] |
[[Category: Burzlaff, N.]] | [[Category: Burzlaff, N.]] | ||
| - | [[Category: Clifton, I | + | [[Category: Clifton, I J.]] |
| - | [[Category: Roach, P | + | [[Category: Roach, P L.]] |
| - | [[Category: Rutledge, P | + | [[Category: Rutledge, P J.]] |
[[Category: ACS]] | [[Category: ACS]] | ||
[[Category: FE2]] | [[Category: FE2]] | ||
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[[Category: sulfoxide]] | [[Category: sulfoxide]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:40:16 2008'' |
Revision as of 12:40, 21 February 2008
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ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (MONOCYCLIC SULFOXIDE-FE COMPLEX)
Overview
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.
About this Structure
1QJF is a Single protein structure of sequence from Emericella nidulans with , and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
The reaction cycle of isopenicillin N synthase observed by X-ray diffraction., Burzlaff NI, Rutledge PJ, Clifton IJ, Hensgens CM, Pickford M, Adlington RM, Roach PL, Baldwin JE, Nature. 1999 Oct 14;401(6754):721-4. PMID:10537113
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