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Title: Characterization of photosynthetic supramolecular assemblies using small angle neutron scattering

We are using small angle neutron scattering (SANS) to resolve structural features of supramolecular assemblies of photosynthetic proteins in liquid and frozen solutions. SANS resolves the size, shape, and structural homogeneity of macromolecular assemblies in samples identical to those used for spectroscopic assays of photosynthetic function. Likely molecular structures of the supramolecular assemblies can be identified by comparing experimental scattering data with scattering profiles calculated for model supramolecular assemblies built from crystal structures of the individual proteins. SANS studies of the Rhodobacter sphaeroides reaction center, RC, presented here, show that the detergent solubilized RC exists in a variety of monomeric and aggregation states. The distribution between monomer and aggregate was found to depend strongly upon detergent, temperature and nature of additives, such as ethylene glycol used for low temperature spectroscopy and polyethylene glycol used for crystallization. Likely aggregate structures are being identified by fitting the experimental scattering profiles with those calculated for model aggregates built-up using the RC crystal structure. This work establishes the foundation for using SANS to identify intermediates in the RC crystallization pathways, and for determining likely structures of complexes formed between the RC and its physiological reaction partners, cytochrome c, and the LHI antenna complex.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
204712
Report Number(s):
ANL/CHM/CP-86353; CONF-9508202-5
ON: DE96005233
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: 10. international photosynthesis congress, Montpellier (France), 20-25 Aug 1995; Other Information: PBD: [1995]
Research Org:
Argonne National Lab., IL (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 55 BIOLOGY AND MEDICINE, BASIC STUDIES; PHOTOSYNTHETIC BACTERIA; SMALL ANGLE SCATTERING; PROTEINS; NEUTRONS; PHOTOSYNTHETIC REACTION CENTERS; MONOMERS