Distribution and self-organization of photosynthetic pigments in micelles: implication for the assembly of light-harvesting complexes and reaction centers in the photosynthetic membrane.

AUTOR(ES)

Scherz, A

RESUMO

The addition of bacteriochlorophylls and bacteriopheophytins to formamide/water, 3:1 (vol/vol), (or water) containing small spherical micelles of Triton X-100 leads to the reorganization of the detergent into micelles that consist of 5000-40,000 amphiphilic molecules. The pigment distribution within the micelles was determined by modified Poisson statistics taking into consideration the various sizes of micelles. Pigment dimerization occurred in micelles with more than a single occupant and was driven by a free-energy change of -4.5 kcal/mol (1 cal = 4.184 J) for bacteriochlorophyll a in formamide/water, -7.6 kcal/mol for bacteriopheophytin a in formamide/water, and -6.6 kcal/mol for bacteriopheophytin a in water. These values correspond to the room temperature equilibrium constants 2.2 x 10(3) M-1, 3.9 x 10(5) M-1, and 7.5 x 10(4) M-1, respectively. The incorporation of bacteriochlorophylls with attached small formamide polymers and the subsequent dimerization of these pigments in the lipid phase provide a model for studying the synergetic organization of polypeptides and bacteriochlorophyll clusters in the photosynthetic membrane.

Documentos Relacionados

• Structure and functional organization of light-harvesting complexes and photochemical reaction centers in membranes of phototrophic bacteria.
• Light-Harvesting Chlorophyll a/b Complexes: Interdependent Pigment Synthesis and Protein Assembly.
• Organization of the Light-Harvesting Complex of Photosystem I and Its Assembly during Plastid Development.
• Reconstitution of chlorophyll a/b light-harvesting complexes: Xanthophyll-dependent assembly and energy transfer
• Light-harvesting chlorophyll a/b-binding protein inserted into isolated thylakoids binds pigments and is assembled into trimeric light-harvesting complex.