1duv
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| , resolution 1.7Å | |||||||
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| Ligands: | , | ||||||
| Activity: | Ornithine carbamoyltransferase, with EC number 2.1.3.3 | ||||||
| Related: | 2OTC, 1OTH
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
CRYSTAL STRUCTURE OF E. COLI ORNITHINE TRANSCARBAMOYLASE COMPLEXED WITH NDELTA-L-ORNITHINE-DIAMINOPHOSPHINYL-N-SULPHONIC ACID (PSORN)
OverviewOverview
The crystal structure is reported at 1.8 A resolution of Escherichia coli ornithine transcarbamoylase in complex with the active derivative of phaseolotoxin from Pseudomonas syringae pv. phaseolicola, N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine. Electron density reveals that the complex is not a covalent adduct as previously thought. Kinetic data confirm that N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine exhibits reversible inhibition with a half-life in the order of approximately 22 h and a dissociation constant of K(D) = 1.6 x 10(-12) m at 37 degrees C and pH 8.0. Observed hydrogen bonding about the chiral tetrahedral phosphorus of the inhibitor is consistent only with the presence of the R enantiomer. A strong interaction is also observed between Arg(57) Nepsilon and the P-N-S bridging nitrogen indicating that imino tautomers of N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine are present in the bound state. An imino tautomer of N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine is structurally analogous to the proposed reaction transition state. Hence, we propose that N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine, with its three unique N-P bonds, represents a true transition state analogue for ornithine transcarbamoylases, consistent with the tight binding kinetics observed.
About this StructureAbout this Structure
1DUV is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Mechanism of inactivation of ornithine transcarbamoylase by Ndelta -(N'-Sulfodiaminophosphinyl)-L-ornithine, a true transition state analogue? Crystal structure and implications for catalytic mechanism., Langley DB, Templeton MD, Fields BA, Mitchell RE, Collyer CA, J Biol Chem. 2000 Jun 30;275(26):20012-9. PMID:10747936
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