1w05: Difference between revisions
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==Overview== | ==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 ... | 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== | ==About this Structure== | ||
1W05 is a | 1W05 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Emericella_nidulans Emericella nidulans] with FE2, SO4 and W05 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Isopenicillin-N_synthase Isopenicillin-N synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.21.3.1 1.21.3.1] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1W05 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: penicillin biosynthesis]] | [[Category: penicillin biosynthesis]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 14:47:51 2007'' | ||
Revision as of 15:42, 5 November 2007
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ISOPENICILLIN N SYNTHASE AMINOADIPOYL-CYSTEINYL-ALANINE-FE COMPLEX
OverviewOverview
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 StructureAbout this Structure
1W05 is a Single protein structure of sequence from Emericella nidulans with FE2, SO4 and W05 as ligands. Active as Isopenicillin-N synthase, with EC number 1.21.3.1 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
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
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