The Length of Esterifying Alcohol Affects the Aggregation Properties of Chlorosomal Bacteriochlorophylls

Chlorosomes, the main light‐harvesting complexes of green photosynthetic bacteria, contain bacteriochlorophyll (BChl) molecules in the form of self‐assembling aggregates. To study the role of esterifying alcohols in BChl aggregation we have prepared a series of bacteriochlorophyllide c (BChlide c) d...

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Bibliographic Details
Published in:Photochemistry and photobiology 2008-09, Vol.84 (5), p.1187-1194
Main Authors: Zupcanova, Anita, Arellano, Juan B., Bina, David, Kopecky, Jiri, Psencik, Jakub, Vacha, Frantisek
Format: Article
Language:English
Subjects:
Alcohol
Alcohols - chemistry
Alkanes - chemistry
Bacteria
Bacterial Proteins - chemistry
Bacteriochlorophylls - chemistry
Changes
Chlorobium - chemistry
Chromatography, High Pressure Liquid
Esters - chemistry
Light-Harvesting Protein Complexes - chemistry
Mass Spectrometry
Molecules
Optical properties
Solvents
Spectrophotometry, Ultraviolet
Water - chemistry
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Summary:Chlorosomes, the main light‐harvesting complexes of green photosynthetic bacteria, contain bacteriochlorophyll (BChl) molecules in the form of self‐assembling aggregates. To study the role of esterifying alcohols in BChl aggregation we have prepared a series of bacteriochlorophyllide c (BChlide c) derivatives differing in the length of the esterifying alcohol (C1, C4, C8 and C12). Their aggregation behavior was studied both in polar (aqueous buffer) and nonpolar (hexane) environments and the esterifying alcohols were found to play an essential role. In aqueous buffer, hydrophobic interactions among esterifying alcohols drive BChlide c derivatives with longer chains into the formation of dimers, while this interaction is weak for BChlides with shorter esterifying alcohols and they remain mainly as monomers. All studied BChlide c derivatives form aggregates in hexane, but the process slows down with longer esterifying alcohols due to competing hydrophobic interactions with hexane molecules. In addition, the effect of the length of the solvent molecules (n‐alkanes) was explored for BChl c aggregation. With an increasing length of n‐alkane molecules, the hydrophobic interaction with the farnesyl chain becomes stronger, leading to a slower aggregation rate. The results show that the hydrophobic interaction is the driving force for the aggregation in an aqueous environment, while in nonpolar solvents it is the hydrophilic interaction.
ISSN:0031-8655
1751-1097
DOI:10.1111/j.1751-1097.2008.00312.x