A contracted form of the trigonal purple membrane of Halobacterium halobium
| Autor: | Richard Henderson, Janet S. Jubb, Michael G. Rossmann |
|---|---|
| Rok vydání: | 1982 |
| Předmět: |
Halobacterium
Aqueous solution Fourier Analysis Chemistry Protein Conformation Resolution (electron density) Carotenoids Crystallography Microscopy Electron Membrane Contractile Proteins Electron diffraction X-Ray Diffraction Structural Biology Phase (matter) Bacteriorhodopsins Molecule Molecular Density Molecular replacement Molecular Biology |
| Zdroj: | Journal of molecular biology. 154(3) |
| ISSN: | 0022-2836 |
| Popis: | A variety of procedures can be used to modify native trigonal (p3) purple membrane of Halobacterium halobium into an altered form with a smaller unit cell. X-ray powder patterns of the new form show the cell dimension a = 59·.5 A, instead of 62·7 A, and totally different intensities. Chemical analyses show a reduction in lipid content in this new form consistent with the smaller unit cell area. R-factor searches of the electron diffraction amplitudes, assuming the projected molecular density to be the same in the two forms, showed the molecule could be satisfactorily fitted into the modified form by a 10° rotation relative to the native. This causes the molecules to be packed more closely, both within each of the groups of three situated about the 3-fold axes as well as between the groups of three. Several new close contacts between helices result, ruling out the possibility that these helices contain amino acids with the same charge at the two aqueous surfaces. The quality of the electron diffraction pattern from the modified membranes is not yet sufficient to help in phase determination of higher resolution data by means of the molecular replacement method. |
| Databáze: | OpenAIRE |
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