Large differences are observed between the crystal and solution quaternary structures of allosteric aspartate transcarbamylase in the R state
✍ Scribed by Dmitri I. Svergun; Claudio Barberato; Michel H. J. Koch; Luc Fetler; Patrice Vachette
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 197 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0887-3585
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✦ Synopsis
Solution scattering curves evaluated from the crystal structures of the T and R states of the allosteric enzyme aspartate transcarbamylase from Escherichia coli were compared with the experimental x-ray scattering patterns. Whereas the scattering from the crystal structure of the T state agrees with the experiment, large deviations reflecting a significant difference between the quaternary structures in the crystal and in solution are observed for the R state. The experimental curve of the R state was fitted by rigid body movements of the subunits in the crystal R structure which displace the latter further away from the T structure along the reaction coordinates of the T=R transition observed in the crystals. Taking the crystal R structure as a reference, it was found that in solution the distance between the catalytic trimers along the threefold axis is 0.34 nm larger and the trimers are rotated by 11°in opposite directions around the same axis; each of the three regulatory dimers is rotated by 9°around the corresponding twofold axis and displaced by 0.14 nm away from the molecular center along this axis. Proteins 27:110-117