Department of Biology, Campus Box 1137, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
Langmuir. 2011 Apr 19;27(8):4816-28. doi: 10.1021/la104532b. Epub 2011 Mar 15.
Chlorosomes, the peripheral light-harvesting antenna complex from green photosynthetic bacteria, are the largest and one of the most efficient light-harvesting antenna complexes found in nature. In contrast to other light-harvesting antennas, chlorosomes are constructed from more than 150,000 self-assembled bacteriochlorophylls (BChls) and contain relatively few proteins that play secondary roles. These unique properties have led to chlorosomes as an attractive candidate for developing biohybrid solar cell devices. In this article, we investigate the temperature and ionic strength effects on the viability of chlorosomes from the photosynthetic green bacterium Chloroflexus aurantiacus using small-angle neutron scattering and dynamic light scattering. Our studies indicate that chlorosomes remain intact up to 75 °C and that salt induces the formation of large aggregates of chlorosomes. No internal structural changes are observed for the aggregates. The salt-induced aggregation, which is a reversible process, is more efficient with divalent metal ions than with monovalent metal ions. Moreover, with treatment at 98 °C for 2 min, the bulk of the chlorosome pigments are undamaged, while the baseplate is destroyed. Chlorosomes without the baseplate remain rodlike in shape and are 30-40% smaller than with the baseplate attached. Further, chlorosomes are stable from pH 5.5 to 11.0. Together, this is the first time such a range of characterization tools have been used for chlorosomes, and this has enabled elucidation of properties that are not only important to understanding their functionality but also may be useful in biohybrid devices for effective light harvesting.
类囊体，一种来自绿色光合细菌的外周光捕获天线复合物，是自然界中发现的最大和最有效的光捕获天线复合物之一。与其他光捕获天线不同，类囊体由超过 150000 个自组装的细菌叶绿素（BChls）组成，并且只包含相对较少的起次要作用的蛋白质。这些独特的性质使得类囊体成为开发生物混合太阳能电池设备的有吸引力的候选者。在本文中，我们使用小角中子散射和动态光散射研究了温度和离子强度对光合绿色细菌 Chloroflexus aurantiacus 类囊体的生存能力的影响。我们的研究表明，类囊体在高达 75°C 的温度下保持完整，并且盐诱导类囊体形成大的聚集体。没有观察到聚集体的内部结构变化。盐诱导的聚集是一个可逆的过程，二价金属离子比单价金属离子更有效地诱导聚集。此外，用 98°C 处理 2 分钟后，大部分类囊体色素未受损，而基板被破坏。没有基板的类囊体保持棒状形状，比附着基板时小 30-40%。此外，类囊体在 pH 值为 5.5 到 11.0 之间稳定。总的来说，这是首次使用如此广泛的表征工具来研究类囊体，这使得阐明不仅对理解其功能很重要，而且可能对用于有效光捕获的生物混合器件也很有用的性质成为可能。
