2AKQ

The structure of bovine B-lactoglobulin A in crystals grown at very low ionic strength

Replaces:  1MFH

Summary for 2AKQ

• Entry DOI: 10.2210/pdb2akq/pdb
• Related: 1beb 1bso 3blg
• Descriptor: Beta-lactoglobulin variant A (2 entities in total)
• Functional Keywords: b-lactoglbulin, crystal lattice, low ionic strength, pseudo-merohedral twinning, transport protein
• Biological source: Bos taurus (cattle)
• Cellular location: Secreted: P02754
• Total number of polymer chains: 4
• Total formula weight: 73549.06

Authors

Adams, J.J.,Anderson, B.F.,Norris, G.E.,Creamer, L.K.,Jameson, G.B. (deposition date: 2005-08-03, release date: 2005-08-16, Last modification date: 2024-10-23)

Primary citation

Adams, J.J.,Anderson, B.F.,Norris, G.E.,Creamer, L.K.,Jameson, G.B.
Structure of bovine beta-lactoglobulin (variant A) at very low ionic strength
J.Struct.Biol., 154:246-254, 2006

PubMed Abstract: Bovine beta-lactoglobulin (BLG) is a globular protein of uncertain physiological function and a member of the lipocalin superfamily of proteins. Here, we present the X-ray structure at 3.0 angstroms of BLG (variant A) from an orthorhombic (P2(1)2(1)2(1)) pseudo-tetragonal crystal form that suffers from pseudo-merohedral twinning (final R(working) = 0.224, R(free) = 0.265). Crystals were grown by dialysis against ultra-purified water (i.e., at very low ionic strength), at pH approximately 5.2 (approximately pI), conditions vastly different from all other BLG structures determined previously. This allows critical assessment of the BLG structure and of the influence that pH, ionic strength, and crystal packing may have on the molecular structure of BLG. The pH-sensitive EF loop is found in the closed conformation characteristic of BLG at pH less than 7 and moderate to high ionic strength. Although the hydrophobic pocket appears to be empty, the presence of highly disordered water molecules cannot be excluded. The dimer interface and the hydrophobic pocket (calyx) are preserved. However, the orientation of the subunits in the dimer varies considerably with crystal form. Structure is deposited with PDB ID 2akq.

PubMed: 16540345
DOI: 10.1016/j.jsb.2005.12.010

Experimental method

X-RAY DIFFRACTION (3 Å)