Macroorganization of Chlorophyll a/b light-harvesting complex in thylakoids and aggregates: information from circular differential scattering

Journal Article · Tue Apr 05 04:00:00 EDT 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00407a027· OSTI ID:5199566

Garab, G; Faludi-Daniel, A; Sutherland, J C; Hind, G

Circular dichroism (CD) and magnetic circular dichroism (MCD) spectra were recorded for spinach thylakoids and for isolated, aggregated chlorophyll a/b light-harvesting pigment-protein complex, in random and magnetically aligned states of orientation at room and low temperatures. The shape and magnitude of the CD signal of most bands strongly depended on the orientation of the thylakoid membranes or the aggregated pigment-protein complex. In both thylakoids and aggregated light-harvesting complexes, however, the MCD spectra of the two different orientations were almost identical. Random and magnetically aligned samples exhibited anomalous, large CD signals outside the bands of pigment absorbance. Lack of similarity between the corresponding MCD and CD spectra showed that the large CD signals are not produced as a distortion of CD of absorbance by light scattering. Instead, these anomalous spectral features are believed to originate in differential selective scattering of circularly polarized light. The results lead to the conclusion that the light-harvesting pigment-protein complex in thylakoid grana forms a helical macroarray with dimensions commensurate with the wavelengths of the anomalous circular dichroism signals. A hypothesis is put forward suggesting a role for these macrodomains in granal organization.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• OSTI ID: 5199566
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:7; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
ABSORPTION SPECTRA
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHLOROPHYLL
CHLOROPHYLL-BINDING PROTEINS
CHLOROPLASTS
DICHROISM
FOOD
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MAGNETIC CIRCULAR DICHROISM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC REACTION CENTERS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
PROTEINS
SPECTRA
SPINACH
VEGETABLES