3pcy
From Proteopedia
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THE CRYSTAL STRUCTURE OF MERCURY-SUBSTITUTED POPLAR PLASTOCYANIN AT 1.9-ANGSTROMS RESOLUTION
Overview
The crystal structure of Hg(II)-plastocyanin has been determined and, refined at a resolution of 1.9 A. The crystals were prepared by soaking, crystals of Cu(II)-plastocyanin from poplar leaves (Populus nigra var., italica) in a solution of a mercuric salt. Replacement of the Cu(II) atom, in plastocyanin by Hg(II) causes only minor changes in the geometry of the, metal site, and there are few significant changes elsewhere in the, molecule. It is concluded that, as in the case of the native protein, the, geometry of the metal site is determined by the polypeptide. The weak, metal-S(methionine) bond found in Cu(II)-plastocyanin remains weak in, Hg(II)-plastocyanin. The "flip" of a proline side chain close to the metal, site from a C gamma-exo conformation in Cu(II)-plastocyanin to a C, gamma-endo conformation in Hg(II)-plastocyanin suggests that this region, of the molecule is particularly flexible. Crystallographic evidence for, the close similarity of the Hg(II)- and Cu(II)-plastocyanin structures was, originally obtained from electron density difference maps at 2.5-A, resolution. The refinement of the structure was begun with a set of atomic, coordinates taken from the structure of Cu(II)-plastocyanin. A Hg(II) atom, was substituted for the Cu(II) atom, and the side chains of 6 residues in, the vicinity of the metal site were omitted. Three series of, stereochemically restrained least-squares refinement calculations were, interspersed with two stages of model adjustment followed by phase, extension. Fifty-nine water molecules were located. The final structure, has a crystallographic residual R = 0.16.
About this Structure
3PCY is a Single protein structure of sequence from Populus nigra with HG as ligand. Full crystallographic information is available from OCA.
Reference
The crystal structure of mercury-substituted poplar plastocyanin at 1.9-A resolution., Church WB, Guss JM, Potter JJ, Freeman HC, J Biol Chem. 1986 Jan 5;261(1):234-7. PMID:3941073
Page seeded by OCA on Tue Nov 20 19:55:18 2007
