1w06
From Proteopedia
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'''ISOPENICILLIN N SYNTHASE AMINOADIPOYL-CYSTEINYL-ALANINE-FE NO COMPLEX''' | '''ISOPENICILLIN N SYNTHASE AMINOADIPOYL-CYSTEINYL-ALANINE-FE NO COMPLEX''' | ||
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[[Category: Long, A J.]] | [[Category: Long, A J.]] | ||
[[Category: Rutledge, P J.]] | [[Category: Rutledge, P J.]] | ||
| - | [[Category: | + | [[Category: B-lactam antibiotic]] |
| - | [[Category: | + | [[Category: Oxidoreductase]] |
| - | [[Category: | + | [[Category: Oxygenase]] |
| - | [[Category: | + | [[Category: Penicillin biosynthesis]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 12:58:39 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 09:58, 3 May 2008
ISOPENICILLIN N SYNTHASE AMINOADIPOYL-CYSTEINYL-ALANINE-FE NO COMPLEX
Overview
Isopenicillin N synthase (IPNS), a non-heme iron(II)-dependent oxidase, catalyzes conversion of the tripeptide delta-(l-alpha-aminoadipoyl)-l-cysteinyl-d-valine (ACV) to bicyclic isopenicillin N (IPN), concomitant with the reduction of dioxygen to two molecules of water. Incubation of the "truncated"substrate analogues delta-(l-alpha-aminoadipoyl)-l-cysteinyl-glycine (ACG) and delta-(l-alpha-aminoadipoyl)-l-cysteinyl-d-alanine (ACA) with IPNS has previously been shown to afford acyclic products, in which the substrate cysteinyl residue has undergone a two-electron oxidation. We report X-ray crystal structures for the anaerobic IPNS/Fe(II)/ACG and IPNS/Fe(II)/ACA complexes, both in the absence and presence of the dioxygen analogue nitric oxide. The overall protein structures are very similar to those of the corresponding IPNS/Fe(II)/ACV complexes; however, significant differences are apparent in the vicinity of the active site iron. The structure of the IPNS/Fe(II)/ACG complex reveals that the C-terminal carboxylate of this substrate is oriented toward the active site iron atom, apparently hydrogen-bonded to an additional water ligand at the metal; this is a different binding mode to that observed in the IPNS/Fe(II)/ACV complex. ACA binds to the metal in a manner that is intermediate between those observed for ACV and ACG. The addition of NO to these complexes initiates conformational changes such that both the IPNS/Fe(II)/ACG/NO and IPNS/Fe(II)/ACA/NO structures closely resemble the IPNS/Fe(II)/ACV/NO complex. These results further demonstrate the feasibility of metal-centered rearrangements in catalysis by non-heme iron enzymes and provide insight into the delicate balance between hydrophilic-hydrophobic interactions and steric effects in the IPNS active site.
About this Structure
1W06 is a Single protein structure of sequence from Emericella nidulans. Full crystallographic information is available from OCA.
Reference
Structural studies on the reaction of isopenicillin N synthase with the truncated substrate analogues delta-(L-alpha-aminoadipoyl)-L-cysteinyl-glycine and delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-alanine., Long AJ, Clifton IJ, Roach PL, Baldwin JE, Rutledge PJ, Schofield CJ, Biochemistry. 2005 May 3;44(17):6619-28. PMID:15850395 Page seeded by OCA on Sat May 3 12:58:39 2008
