Bystrova M I, Mal'gosheva I N, Krasnovskiĭ A A
Mol Biol (Mosk). 1979 May-Jun;13(3):582-94.
The intermolecular interaction of bacteriochlorophyll c and its pheophytin was studied in nonpolar solvents and solid films with the aid of absorption and infra-red (in the region of 1800--1600 and 3800--3000 cm-1) spectra. The influence of water removing and its addition on these spectra has been investigated. Besides the effect of pyridine treatment and pigment concentration were examined. The self-assemblage of all types of bacteriochlorophyll c aggregated forms absorbing in the range 680--745 nm is due to the formation of intermolecular bonds in which keto groups of cyclopentanone rings take part. Keto groups form coordinate bonds with the central magnesium atom (keto-C = O...Mg). Hydroxyl groups interact coordinately with magnesium and simultaneously form hydrogen bonds with pyrrol nitrogen. In contrast to chlorophyll a and bacteriochlorophyll a, water molecules in the case of bacteriochlorophyll c do not participate in the intermolecular bond formation in the course of long-wave aggregated forms production. The thermostability of bacteriochlorophyll c aggregates and their rather high stability to desaggregating agents is related to the mentioned peculiarities of their structure. Bacteriopheophytin c in any state (solution or solid film) is not capable to form intermolecular bonds by its carbonyl groups and long-wave aggregates. The specific features of the assemblage of bacteriochlorophyll c aggregates modelling antenna of the green photosynthetic bacteria are discussed.
借助吸收光谱和红外光谱（在1800 - 1600 cm-1和3800 - 3000 cm-1区域），研究了细菌叶绿素c及其脱镁叶绿素在非极性溶剂和固体薄膜中的分子间相互作用。研究了除水及其添加对这些光谱的影响。此外，还考察了吡啶处理的效果和色素浓度。所有类型在680 - 745 nm范围内吸收的细菌叶绿素c聚集形式的自组装是由于分子间键的形成，环戊酮环的酮基参与其中。酮基与中心镁原子形成配位键（酮 - C = O...Mg）。羟基与镁配位相互作用，同时与吡咯氮形成氢键。与叶绿素a和细菌叶绿素a不同，在细菌叶绿素c的情况下，水分子在长波聚集形式产生过程中不参与分子间键的形成。细菌叶绿素c聚集体的热稳定性及其对解聚剂的相当高的稳定性与它们结构的上述特性有关。任何状态（溶液或固体薄膜）的细菌脱镁叶绿素c都不能通过其羰基形成分子间键和长波聚集体。讨论了模拟绿色光合细菌天线的细菌叶绿素c聚集体组装的具体特征。
