1i4z
From Proteopedia
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| , resolution 2.10Å | |||||||
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| Ligands: | |||||||
| Related: | 999
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THE CRYSTAL STRUCTURE OF PHASCOLOPSIS GOULDII L98Y METHEMERYTHRIN
Overview
Reported are the X-ray crystal structures of recombinant Phascolopsis gouldii methemerythrin (1.8-A resolution) and the structure of an O2-binding-pocket mutant, L98Y methemerythrin (2.1-A resolution). The L98Y hemerythrin (Hr) has a greatly enhanced O2 affinity, a slower O2 dissociation rate, a larger solvent deuterium isotope effect on this rate, and a greater resistance to autoxidation relative to the wild-type protein. The crystal structures show that the hydrophobic binding pocket of Hr can accommodate substitution of a leucyl by a tyrosyl side chain with relatively minor structural rearrangements. UV/vis and resonance Raman spectra show that in solution L98Y methemerythrin contains a mixture of two diiron site structures differing by the absence or presence of an Fe(III)-coordinated phenolate. However, in the crystal, only one L98Y diiron site structure is seen, in which the Y98 hydroxyl is not a ligand, but instead forms a hydrogen bond to a terminal hydroxo/aqua ligand to the nearest iron. Based on this crystal structure, we propose that in the oxy form of L98Y hemerythrin the non-polar nature of the binding pocket favors localization of the Y98 hydroxyl near the O2 binding site, where it can donate a hydrogen bond to the hydroperoxo ligand. The stabilizing Y98OH-O2H-interaction would account for all of the altered O2 binding properties of L98Y Hr listed above.
About this Structure
1I4Z is a Single protein structure of sequence from Phascolopsis gouldii. Full crystallographic information is available from OCA.
Reference
The crystal structures of Phascolopsis gouldii wild type and L98Y methemerythrins: structural and functional alterations of the O2 binding pocket., Farmer CS, Kurtz DM Jr, Liu ZJ, Wang BC, Rose J, Ai J, Sanders-Loehr J, J Biol Inorg Chem. 2001 Apr;6(4):418-29. PMID:11372200
Page seeded by OCA on Sun Mar 30 21:14:43 2008
