Journal
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
Volume 64, Issue -, Pages 567-588Publisher
BLACKWELL PUBLISHING
DOI: 10.1107/S0907444908006082
Keywords
-
Ask authors/readers for more resources
The valence electron density of the protein human aldose reductase was analyzed at 0.66 angstrom resolution. The methodological developments in the software MoPro to adapt standard charge-density techniques from small molecules to macromolecular structures are described. The deformation electron density visible in initial residual Fourier difference maps was significantly enhanced after high-order refinement. The protein structure was refined after transfer of the experimental library multipolar atom model (ELMAM). The effects on the crystallographic statistics, on the atomic thermal displacement parameters and on the structure stereochemistry are analyzed. Constrained refinements of the transferred valence populations P-val and multipoles P-lm were performed against the X-ray diffraction data on a selected substructure of the protein with low thermal motion. The resulting charge densities are of good quality, especially for chemical groups with many copies present in the polypeptide chain. To check the effect of the starting point on the result of the constrained multipolar refinement, the same charge-density refinement strategy was applied but using an initial neutral spherical atom model, i.e. without transfer from the ELMAM library. The best starting point for a protein multipolar refinement is the structure with the electron density transferred from the database. This can be assessed by the crystallographic statistical indices, including R-free, and the quality of the static deformation electron-density maps, notably on the oxygen electron lone pairs. The analysis of the main-chain bond lengths suggests that stereochemical dictionaries would benefit from a revision based on recently determined unrestrained atomic resolution protein structures.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available