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http://dspace.mediu.edu.my:8181/xmlui/handle/10261/3646| Title: | Effect of Carotenoids and Monogalactosyl Diglyceride on Bacteriochlorophyll c Aggregates in Aqueous Buffer: Implications for the Self-assembly of Chlorosomes |
| Keywords: | Chlorosome Bacteriochlorophyll Aggregates Carotenoid Monogalactosyl diglyceride Dimers |
| Publisher: | American Society for Photobiology |
| Description: | Aggregation of bacteriochlorophyll (BChl) c from chlorosomes, the main light-harvesting complex of green bacteria, has been studied in aqueous buffer. Unlike other chlorophyll-like molecules, BChl c is rather soluble in aqueous buffer, forming dimers. When BChl c is mixed with carotenoids (Car), the BChl c Qy transition is further redshifted, in respect to that of monomers and dimers. The results suggest that Car are incorporated in the aggregates and induce further aggregation of BChl c. The redshift of the BChl c Qy band is proportional to the Car concentration. In contrast, the mixture of bacteriochlorophyllide (BChlide) c, which lacks the nonpolar esterifying alcohol, does not form aggregates with Car in aqueous buffer or nonpolar solvents. Instead, the position of the BChlide c Qy transition remains unshifted in respect to that of the monomeric molecule, and Car precipitates with the course of time in aqueous buffer. Similar effects on both BChl c and BChlide c are also observed when monogalactosyl diglyceride (MGDG), which forms the monolayer envelope of chlorosomes, is used instead of (or together with) Car. The results show that the hydrophobic interactions of the BChl c esterifying alcohols with themselves and the nonpolar carbon skeleton of Car, or the fatty acid tails of MGDG, are essential driving forces for BChl aggregation in chlorosomes. Spanish Minitry of Science and Technology (AGL2003-00045). Spanish CSIC Marina Bueno Program This work was supported by the Czech Science Foundation and Czech Ministry of Education, Youth and Sports (contracts 206/02/0942, LN00A141). J.B.A. is very grateful to the CSIC Marina Bueno program and the Spanish Ministry of Science and Technology for financial support(project reference AGL2003-00045). Peer reviewed |
| URI: | http://dspace.mediu.edu.my:8181/xmlui/handle/10261/3646 |
| Other Identifiers: | Photochemistry and Photobiology (2004) 80:572-578. http://hdl.handle.net/10261/3646 10.1111/j.1751-1097.2004.tb00131.x |
| Appears in Collections: | Digital Csic |
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