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1hb4

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{{STRUCTURE_1hb4| PDB=1hb4 | SCENE= }}
{{STRUCTURE_1hb4| PDB=1hb4 | SCENE= }}
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'''ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (OXYGEN EXPOSED PRODUCT FROM ANAEROBIC ACOV FE COMPLEX)'''
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===ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (OXYGEN EXPOSED PRODUCT FROM ANAEROBIC ACOV FE COMPLEX)===
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==Overview==
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BACKGROUND: Isopenicillin N synthase (IPNS) catalyses formation of bicyclic isopenicillin N, precursor to all penicillin and cephalosporin antibiotics, from the linear tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine. IPNS is a non-haem iron(II)-dependent enzyme which utilises the full oxidising potential of molecular oxygen in catalysing the bicyclisation reaction. The reaction mechanism is believed to involve initial formation of the beta-lactam ring (via a thioaldehyde intermediate) to give an iron(IV)-oxo species, which then mediates closure of the 5-membered thiazolidine ring. RESULTS: Here we report experiments employing time-resolved crystallography to observe turnover of an isosteric substrate analogue designed to intercept the catalytic pathway at an early stage. Reaction in the crystalline enzyme-substrate complex was initiated by the application of high-pressure oxygen, and subsequent flash freezing allowed an oxygenated product to be trapped, bound at the iron centre. A mechanism for formation of the observed thiocarboxylate product is proposed. CONCLUSIONS: In the absence of its natural reaction partner (the N-H proton of the L-cysteinyl-D-valine amide bond), the proposed hydroperoxide intermediate appears to attack the putative thioaldehyde species directly. These results shed light on the events preceding beta-lactam closure in the IPNS reaction cycle, and enhance our understanding of the mechanism for reaction of the enzyme with its natural substrate.
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(as it appears on PubMed at http://www.pubmed.gov), where 11755401 is the PubMed ID number.
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{{ABSTRACT_PUBMED_11755401}}
==About this Structure==
==About this Structure==
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[[Category: Oxygenase]]
[[Category: Oxygenase]]
[[Category: Penicillin biosynthesis]]
[[Category: Penicillin biosynthesis]]
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Revision as of 04:55, 1 July 2008

Image:1hb4.png

Template:STRUCTURE 1hb4

ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (OXYGEN EXPOSED PRODUCT FROM ANAEROBIC ACOV FE COMPLEX)

Template:ABSTRACT PUBMED 11755401

About this Structure

1HB4 is a Single protein structure of sequence from Emericella nidulans. Full crystallographic information is available from OCA.

Reference

Alternative oxidation by isopenicillin N synthase observed by X-ray diffraction., Ogle JM, Clifton IJ, Rutledge PJ, Elkins JM, Burzlaff NI, Adlington RM, Roach PL, Baldwin JE, Chem Biol. 2001 Dec;8(12):1231-7. PMID:11755401

Page seeded by OCA on Tue Jul 1 07:55:41 2008

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