High-resolution electron crystallography of light-harvesting chlorophyll a/b-protein complex in three different media.
Large two-dimensional crystals of the light-harvesting chlorophyll a/b-protein complex (LHC-II) from the photosynthetic membrane of pea chloroplasts were grown by a new method from detergent solution. The structure of these crystals was examined by electron crystallography, using three different media to preserve high-resolution detail: vitrified water, glucose and tannin. The crystals diffracted electrons to at least 3.2 A resolution in all three media. R-factors between the three data sets of electron diffraction amplitudes ranged from 6.4% to 14.3%. Fourier difference maps were generated and compared to a projection map of the complex at 3.4 A resolution. No significant differences were found, proving that all three media preserved the native structure of LHC-II at high resolution. The probability of recording high-quality electron diffraction patterns with tannin was 90%. With glucose and water this probability was lower by a factor of 10 to 20, suggesting that tannin may be preferable as a preserving medium for sensitive biological specimens.
Wang
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European Molecular Biology Laboratory, Germany.
Kühlbrandt
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D002734:Chlorophyll / Q000737:chemistry*; D000077194:Chlorophyll A; D003460:Crystallization; D003461:Crystallography; D003902:Detergents; D007887:Fabaceae; D005583:Fourier Analysis; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D010946:Plants, Medicinal; D012996:Solutions; D014961:X-Ray Diffraction
D003902:Detergents; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D012996:Solutions; D002734:Chlorophyll; C037184:chlorophyll b; D000077194:Chlorophyll A