1DZK: Porcine Odorant Binding Protein Complexed With Pyrazine (2-Isobutyl-3-Metoxypyrazine)

Citation:
Abstract
Porcine odorant binding protein (pOBP) is a monomer of 157 amino acid residues, purified in abundance from pig nasal mucosa. In contrast to the observation on lipocalins as retinol binding protein (RBP), major urinary protein (MUP) or bovine odorant binding protein (bOBP), no naturally occurring ligand was found in the beta-barrel cavity of pOBP. Porcine OBP was therefore chosen as a simple model for structure/function studies with odorant molecules. In competition experiments with tritiated pyrazine, the affinity of pOBP towards several odorant molecules belonging to different chemical classes has been found to be of the micromolar order, with a 1:1 stoichiometry. The X-ray structures of pOBP complexed to these molecules were determined at resolution between 2.15 and 1.4 A. As expected, the electron density of the odorant molecules was observed into the hydrophobic beta-barrel of the lipocalin. Inside this cavity, very few specific interactions were established between the odorant molecule and the amino acid side-chains, which did not undergo significant conformational change. The high B-factors observed for the odorant molecules as well as the existence of alternative conformations reveal a non-specific mode of binding of the odorant molecules in the cavity.
PDB ID: 1DZKDownload
MMDB ID: 15148
PDB Deposition Date: 2000/3/1
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 1.48  Å
Source Organism:
Similar Structures:
Biological Unit for 1DZK: monomeric; determined by author and by software (PISA)
Molecular Components in 1DZK
Label Count Molecule
Protein (1 molecule)
1
Odorant-binding Protein(Gene symbol: OBP)
Molecule annotation
Chemical (1 molecule)
1
1
* Click molecule labels to explore molecular sequence information.

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