Investigation on the crystal structure of proteins and their complexes in solution from combined TEM techniques and solubility measurements: the case of endo-1,3(4)-β-glucanase
✍ Scribed by V Guyot Ferréol; X Hagnerelle; A Gaunand; E Larquet; M Caussette; B Lindet
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 264 KB
- Volume
- 52
- Category
- Article
- ISSN
- 0959-8103
- DOI
- 10.1002/pi.1233
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✦ Synopsis
Abstract
Endo‐1,3(4)‐β‐glucanase was crystallized from a crude extract of protein solution by addition of a salt A^+^, X^−^. Optical microscopy showed needle‐shaped polydisperse crystals with a mean size of 10 µm. Using transmission electron microscopy with specific settings allows one to characterize the ordered arrays of a thin protein crystal and to determine the parameters of the crystal lattice. The results suggest that the unit cell of a endo‐1,3(4)‐β‐glucanase crystal may consist in the association of a given number of these proteins. Such oligomers have already been seen for other proteins. The solubility of endo‐1,3(4)‐β‐glucanase in aqueous solution was determined for several X^−^ concentrations using BCA assay (titration of the total protein in solution) and electrophoresis. The new data are in agreement with a new simple model based on equilibrium between the oligomer in solution and neutral and charged X^−^ complexes of the protein in the monomer state. The model provides a new approach to the usual salting‐in/salting‐out description of protein solubility. Copyright © 2003 Society of Chemical Industry