The rate and extent of phosphorylation of the two light-harvesting chlorophyll a/b binding protein complex (LHC-II) polypeptides in isolated spinach thylakoids

1987 ◽  
Vol 893 (2) ◽  
pp. 333-341 ◽  
Author(s):  
Khalid Islam
Keyword(s):  
Chlorophyll A ◽  
Protein Complex ◽  
Light Harvesting ◽  
Binding Protein ◽  
Lhc Ii ◽  
Spinach Thylakoids

High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

1990 ◽  
Vol 48 (1) ◽  
pp. 610-610
Author(s):  
Werner Kühlbrandt ◽  
Da Neng Wang ◽  
K.H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Structural Integrity ◽  
Light Harvesting ◽  
Lhc Ii ◽  
Diffraction Patterns ◽  
Difference Fourier ◽  
2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

The Oligomeric Arrangement of the Light-Harvesting Chlorophyll a/6-Protein Complex of Photosystem II

1994 ◽  
Vol 49 (5-6) ◽  
pp. 337-342 ◽  
Author(s):  
Grzegorz Jackowski ◽  
Ewa Kluck
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Light Harvesting ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Dianthus Caryophyllus ◽  
Lhc Ii ◽  
Induced Aggregation ◽  
Oligomeric Forms

Abstract The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHC II) was isolated from carnation (Dianthus caryophyllus L.) leaves by K+-induced aggregation of n-hep-tylthioglucoside-treated photosystem II particles. When solubilized with a mixture of lithium docedyl sulphate, octyl-β-D-glucopyranoside and dodecyl-β-D-maltoside the LHC II was re­ solved by mild sodium dodecyl sulphate-polyacrylamide gel electrophoresis into four oligo­meric forms and a monomeric one. LHC II contained five major polypeptides only two of which (27 and 26 kDa) were found to be its authentic components. The oligomeric forms of LHC II were found to differ in the stoichiometric ratios of the polypeptides present. The 26 kD a polypeptide was enriched in the largest oligomeric forms while the 27 kDa polypep­tide tended to form a monomer or to assemble as lower oligomeric states of LHC II.

Image Processing of Thin Three-Dimensional Crystals of the Light-Harvesting Chlorophyll a/b-Protein Complex from Chloroplast Membranes

1988 ◽  
Vol 46 ◽  
pp. 148-149
Author(s):  
Werner Kühlbrandt
Keyword(s):  
Chlorophyll A ◽  
Protein Complex ◽  
Fourier Transforms ◽  
Light Harvesting ◽  
Three Dimensional ◽  
Optical Diffraction ◽  
Step Size ◽  
Chloroplast Membranes ◽  
Lhc Ii ◽  
Hexagonal Crystals

Thin three-dimensional, hexagonal crystals of the light—harvesting chlorophyll a/b—protein complex (LHC II) from pea chloroplast membranes diffract electrons to 3.7 Å resolution when preserved in glucose or tannin. The symmetry of the diffraction pattern (6mm), the dimensions of the unit cell in projection (a = 127 Å) and micrographs of negatively stained specimens suggested that the hexagonal crystals were stacks of two-dimensional crystals of p321 symmetry. Low—dose (1 —2 electrons/Å2) electron micrographs of thin three-dimensional crystals preserved in tannin were recorded in an attempt to determine the structure of this integral membrane protein complex at high resolution, initially in projection. The best images showed sharp diffraction spots at 12 — 14 Å resolution when examined by optical diffraction. Image areas measuring up to 40 x 40 mm2 were densitometered at a step size corresponding to 3 Å or less at the specimen and computer processed to correct for lattice distortions, using programmes by R.Henderson and J.M.Baldwin. Fourier transforms of the distortion—corrected images showed reflections above background level to 6 Å resolution.

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