Low-resolution detergent tracing in protein crystals using xenon or krypton to enhance X-ray contrast

Sauer, Oliver and Roth, Michel and Schirmer, Tilman and Rummel, Gabriele and Kratky, Christoph. (2002) Low-resolution detergent tracing in protein crystals using xenon or krypton to enhance X-ray contrast. Acta Crystallographica. Section D, Biological Crystallography, Vol. 58, Pt. 1. pp. 60-69.

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Official URL: http://edoc.unibas.ch/dok/A5258255

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Xenon and krypton show different solubilities in polar versus apolar solvents. Therefore, these noble gases should accumulate in apolar regions of protein crystals. Specifically, they should accumulate in lipid and detergent solvent regions within crystals of membrane proteins, which can be used as a basis for contrast-variation experiments to distinguish such apolar solvent regions from the aqueous phase by a low-resolution X-ray diffraction experiment. This possibility was explored with the OmpF porin, one of the general diffusion pores of the Escherichia coli outer membrane. Trigonal crystals were exposed to elevated pressures of the two noble gases (up to 10(7) Pa) for several minutes and subsequently flash-cooled to liquid-nitrogen temperatures. Both rare gases bind to a number of 'specific' sites, which can be classified as 'typical' noble-gas binding sites. Compared with a representative water-soluble protein, they are however much more abundant in OmpF. In addition, a very large number of weakly populated sites are observed which accumulate in the region of the 'detergent belt' for crystals exposed to xenon. After application of a Fourier-filtering protocol, low-resolution images of the detergent belt can be obtained. The resulting maps are similar to maps obtained from low-resolution neutron diffraction experiments on contrast-matched crystals.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Schirmer)
UniBasel Contributors:Schirmer, Tilman
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:07 Aug 2015 12:05
Deposited On:22 Mar 2012 13:20

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