1hb2: Difference between revisions
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{{STRUCTURE_1hb2| PDB=1hb2 | SCENE= }} | |||
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'''ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (OXYGEN EXPOSED PRODUCT FROM ANAEROBIC ACOV FE COMPLEX)''' | '''ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (OXYGEN EXPOSED PRODUCT FROM ANAEROBIC ACOV FE COMPLEX)''' | ||
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[[Category: Roach, P L.]] | [[Category: Roach, P L.]] | ||
[[Category: Rutledge, P J.]] | [[Category: Rutledge, P J.]] | ||
[[Category: | [[Category: Antibiotic biosynthesis]] | ||
[[Category: | [[Category: B-lactam antibiotic]] | ||
[[Category: | [[Category: Oxygenase]] | ||
[[Category: | [[Category: Penicillin biosynthesis]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 18:39:17 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 18:39, 2 May 2008
ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (OXYGEN EXPOSED PRODUCT FROM ANAEROBIC ACOV FE COMPLEX)
OverviewOverview
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.
About this StructureAbout this Structure
1HB2 is a Single protein structure of sequence from Emericella nidulans. Full crystallographic information is available from OCA.
ReferenceReference
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 Fri May 2 18:39:17 2008