Download MendeleyProline cis-trans isomers in calbindin D9k observed by X-ray crystallography.
Svensson, L.A., Thulin, E., Forsen, S.(1992) J Mol Biology 223: 601-606
- PubMed: 1542107
- DOI: https://doi.org/10.1016/0022-2836(92)90976-q
- Primary Citation of Related Structures:
4ICB - PubMed Abstract:
In a structure of recombinant bovine calbindin D9k, determined crystallographically to 1.6 A resolution, a proline in mixed, approximately equally populated, cis and trans conformation is observed. Isomers of this kind have not been reported in structure determinations of calbindin D9k to 2.3 A resolution or in any other crystallographically determined protein structure. The cis-trans isomerization occurs at the peptide bond between Gly42 and Pro43, which is in agreement with results from two-dimensional 1H nuclear magnetic resonance spectroscopy experiments on solutions of calbindin D9k. Alternative backbone stretches have been modeled and refined by stereochemical restrained least-squares refinement for the segment Lys41 to Pro43. The final R-value was 0.188. The structural perturbations accompanying the cis-trans isomerization are found to be very localized. The largest positional differences are observed at residue Gly42, in which the alternative positions of the oxygen atom are 3.6 A apart.
Organizational Affiliation:
Department of Molecular Biophysics, University of Lund, Sweden.
