Experimental Data Snapshot

  • Resolution: 1.7 Å

wwPDB Validation 3D Report Full Report

This is version 1.2 of the entry. See complete history


Refined structure of baboon alpha-lactalbumin at 1.7 A resolution. Comparison with C-type lysozyme.

Acharya, K.R.Stuart, D.I.Walker, N.P.Lewis, M.Phillips, D.C.

(1989) J.Mol.Biol. 208: 99-127

  • PubMed Abstract: 
  • The solution of the structure of alpha-lactalbumin from baboon milk (Papio cynocephalus) at 4.5 A resolution using the isomorphous replacement method has been reported previously. Initial refinement on the basis of these low-resolution studies was no ...

    The solution of the structure of alpha-lactalbumin from baboon milk (Papio cynocephalus) at 4.5 A resolution using the isomorphous replacement method has been reported previously. Initial refinement on the basis of these low-resolution studies was not successful because of the poor isomorphism of the best heavy-atom derivative. Because of the striking similarity between the structure of lysozyme and alpha-lactalbumin, a more cautious molecular replacement approach was tried to refine the model. Using hen egg-white lysozyme as the starting model, preliminary refinement was performed using heavily constrained least-squares minimization in reciprocal space. The model was further refined using stereochemical restraints at 1.7 A resolution to a conventional crystallographic residual of 0.22 for 1141 protein atoms. In the final model, the root-mean-square deviation from ideality for bond distances is 0.015 A, and for angle distances it is 0.027 A. The refinement was carried out using the human alpha-lactalbumin sequence and "omit maps" calculated during the course of refinement indicated eight possible sequence changes in the baboon alpha-lactalbumin X-ray sequence. During the refinement, a tightly bound calcium ion and 150 water molecules, of which four are internal, have been located. Some of the water molecules were modelled for disordered side-chains. The co-ordination around the calcium is a slightly distorted pentagonal bipyramid. The Ca-O distances vary from 2.2 A to 2.6 A, representing a tight calcium-binding loop in the structure. The calcium-binding fold only superficially resembles the "EF-hand" and presumably has no evolutionary relationship with other EF-hand structures. The overall structure of alpha-lactalbumin is very similar to that of lysozyme. All large deviations occur in the loops where all sequence deletions and insertions are found. The C terminus appears to be rather flexible in alpha-lactalbumin compared to lysozyme. The experimental evidence supports the earlier predictions for the alpha-lactalbumin structure that were based upon the assumption that alpha-lactalbumin and lysozyme have similar three-dimensional structures, with minimal deletions and insertions. A detailed comparison of the two structures shows striking features as well as throwing some light on the evolution of these two proteins from a common precursor.

    Related Citations: 
    • Alpha-Lactalbumin Possesses a Novel Calcium Binding Loop
      Stuart, D.I.,Acharya, K.R.,Walker, N.P.C.,Smith, S.G.,Lewis, M.,Phillips, D.C.
      (1986) Nature 324: 84
    • Crystallographic Analysis of the Three-Dimensional Structure of Baboon Alpha-Lactalbumin at Low Resolution. Homology with Lysozyme
      Smith, S.G.,Lewis, M.,Aschaffenburg, R.,Fenna, R.E.,Wilson, I.A.,Sundaralingam, M.,Stuart, D.I.,Phillips, D.C.
      (1987) Biochem.J. 242: 353
    • Crystallography of Alpha-Lactalbumin. III. Crystals of Baboon Milk Alpha-Lactalbumin
      Aschaffenburg, R.,Fenna, R.E.,Phillips, D.C.,Smith, S.G.,Buss, D.H.,Jeness, R.,Thompson, M.P.
      (1979) J.Mol.Biol. 127: 135

    Organizational Affiliation

    Laboratory of Molecular Biophysics, University of Oxford, U.K.


Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
123Papio cynocephalusN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
Query on CA

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 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Resolution: 1.7 Å
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 35.500α = 90.00
b = 69.100β = 90.00
c = 46.100γ = 90.00
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1989-10-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance