Characterization of circular differential selective scattering in randomly and magnetically oriented chloroplasts and light harvesting chlorophyll a/b aggregates

Conference · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6882487

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

Comparative circular dichroism studies were carried out in chloroplasts and the aggregated chlorophyll a/b light harvesting pigment protein complex (LHC). Much of the intense circular dichroism (CD) signal of chloroplasts and that of aggregated, isolated LHC were found to originate in circular differential light scattering (CDS). The difference spectra obtained between the CD spectra of randomly and magnetically oriented thylakoids resembled the selective light scattering spectra of chloroplasts. Furthermore, orientation-dependent changes in the CDS signal outside the principal absorbance bands were correlated with changes in the non-selective forward light scattering. These results provide evidence of a significant contribution by CDS to the CD spectrum of chloroplasts. A comparison between the CD signals of chloroplasts and aggregated LHC revealed that both preparations exhibit ''anomalous'' CD bands. The spectral shape and amplitude of these bands are changed dramatically upon magnetic alignment of the particles. These similarities are suggestive of the existence of similar helical domains in chloroplasts and the isolated LHC aggregate; hence our experimental results support the hypothesis of Faludi-Daniel and Mustardy that the LHC in the thylakoid membrane is aggregated in a liquid crystal-like structure resembling that which self-assembles in vitro. 17 refs., 4 figs.

• Research Organization: Brookhaven National Lab., Upton, NY (USA); Magyar Tudomanyos Akademia, Szeged. Biologiai Kutato Koezpontja
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6882487
• Report Number(s): BNL-38815; CONF-860808-10; ON: DE87002586
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
CELL CONSTITUENTS
CHLOROPHYLL-BINDING PROTEINS
CHLOROPLASTS
DICHROISM
LAMELLAE
MAGNETIC FIELDS
MEMBRANES
ORGANIC COMPOUNDS
PHOTOSYNTHETIC MEMBRANES
PHOTOSYNTHETIC REACTION CENTERS
PROTEINS