Experimental Data Snapshot

  • Resolution: 1.6 Å

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Accuracy and precision in protein crystal structure analysis: two independent refinements of the structure of poplar plastocyanin at 173 K.

Fields, B.A.Bartsch, H.H.Bartunik, H.D.Cordes, F.Guss, J.M.Freeman, H.C.

(1994) Acta Crystallogr.,Sect.D 50: 709-730

  • DOI: 10.1107/S0907444994003021
  • Primary Citation of Related Structures:  1PND

  • PubMed Abstract: 
  • The structure of the copper protein plastocyanin from poplar leaves (Populus nigra var. italica) at 173 K has been subjected to two independent refinements, using a single set of synchrotron X-ray data at 1.6 A resolution. Energy-restrained refinemen ...

    The structure of the copper protein plastocyanin from poplar leaves (Populus nigra var. italica) at 173 K has been subjected to two independent refinements, using a single set of synchrotron X-ray data at 1.6 A resolution. Energy-restrained refinement using the program EREF resulted in lower root-mean-square deviations from ideal geometry (e.g. 0.011 A for bond lengths) but a higher residual R (0.153) than restrained least-squares refinement using the program PROLSQ (0.014 A, 0.132). Electron-density difference maps in both refinements provided evidence for disorder at some side chains and solvent atoms, and the PROLSQ refinement made allowance for this disorder. The number of solvent sites identified at the 4sigma(rho) level was 171 in the EREF refinement and 189 in the PROLSQ refinement; 159 of the solvent sites are common to both refinements within 1 A. The root-mean-square differences between the atomic positions produced by the two refinements are 0.08 A for C(alpha) atoms, 0.08 A for backbone atoms and 0.12 A for all non-H atoms (excluding six obvious outliers) of the protein molecule. The two sets of Cu-ligand bond lengths differ by up to 0.07 A, and the ligand-Cu-ligand angles by up to 7 degrees. At 173 K the volume of the unit cell is 4.2% smaller than at 295 K. Greater order in the solvent region is indicated by the location of 79 more solvent sites, the identification of extensive networks of hydrogen-bonded rings of solvent molecules, and a general decrease in the thermal parameters. Within the unit cell, the protein molecules are significantly translated and rotated from their positions at ambient temperature. An important structural change at low temperature is a 180 degrees flip of the peptide group at Ser48-Gly49. Nearly all other significant differences between the structures of the protein at 173 and 295 K occur at exposed side chains. If the backbone atoms in the 173 and 295 K structures are superposed, excluding atoms involved in the peptide flip, the root-mean- square difference between the positions of 393 atoms is 0.25 A. Two internal water molecules, not included in previous descriptions of poplar plastocyanin, have been located. The plastocyanin Cu-site geometry at 173 K is not significantly different from that at 295 K. If plastocyanin undergoes a change in Cu-site geometry at low temperature, as has been suggested on the basis of resonance Raman spectroscopic evidence, then the change is not detected within the limits of precision of the present results.

    Related Citations: 
    • Structure of Oxidised Poplar Plastocyanin at 1.6 Angstroms Resolution
      Guss, J.M.,Freeman, H.C.
      (1983) J.Mol.Biol. 169: 521
    • Preliminary Crystallographic Data for a Copper Containing Protein, Plastocyanin
      Chapman, G.V.,Colman, P.M.,Freeman, H.C.,Guss, J.M.,Murata, M.,Norris, V.A.,Ramashaw, J.A.M.,Venkatappa, M.P.
      (1977) J.Mol.Biol. 110: 187
    • Accuracy and Precision in Protein Structure Analysis: Restrained Least-Squares Refinement of the Structure of Poplar Plastocyanin at 1.33 Angstroms Resolution
      Guss, J.M.,Bartunik, H.D.,Freeman, H.C.
      (1992) Acta Crystallogr.,Sect.B 48: 790
    • X-Ray Crystal Structure Analysis of Plastocyanin at 2.7 Angstroms Resolution
      Colman, P.M.,Freeman, H.C.,Guss, J.M.,Murata, M.,Norris, V.A.,Ramshaw, J.A.M.,Venkatappa, M.P.
      (1978) Nature 272: 319

    Organizational Affiliation

    Department of Inorganic Chemistry, University of Sydney, Australia.


Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
99Populus nigraGene Names: PETE
Find proteins for P00299 (Populus nigra)
Go to UniProtKB:  P00299
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
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 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Resolution: 1.6 Å
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 29.180α = 90.00
b = 46.290β = 90.00
c = 56.640γ = 90.00
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1994-01-31
    Type: Initial release
  • Version 1.1: 2008-03-03
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2012-08-08
    Type: Derived calculations