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首页> 外文期刊>Biochemistry >CP-MAS C-13-NMR DIPOLAR CORRELATION SPECTROSCOPY OF C-13-ENRICHED CHLOROSOMES AND ISOLATED BACTERIOCHLOROPHYLL C AGGREGATES OF CHLOROBIUM TEPIDUM - THE SELF-ORGANIZATION OF PIGMENTS IS THE MAIN STRUCTURAL FEATURE OF CHLOROSOMES
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CP-MAS C-13-NMR DIPOLAR CORRELATION SPECTROSCOPY OF C-13-ENRICHED CHLOROSOMES AND ISOLATED BACTERIOCHLOROPHYLL C AGGREGATES OF CHLOROBIUM TEPIDUM - THE SELF-ORGANIZATION OF PIGMENTS IS THE MAIN STRUCTURAL FEATURE OF CHLOROSOMES

机译：CP-MAS C-13-NMR二聚体相关光谱，富集C-13的叶绿藻和分离的叶绿藻细菌C团聚体-色素的自组织是叶绿体的主要结构特征

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Magic angle spinning (MAS) NMR dipolar correlation spectroscopy was applied for the first time to a biologically intact system, the light-harvesting chlorosomes of the green photosynthetic bacterium Chlorobium tepidum. The MAS spectra provide evidence that the self-organization of many thousands of bacteriochlorophyll c (BChl c) molecules is the predominant structural feature of the chlorosome. C-13-Enriched chlorosomes were prepared from nonuniformly labeled cultures grown with (NaHCO3)-C-13 as the main carbon source and from a uniformly C-13-labeled culture grown with (NaHCO3)-C-13 as the sole carbon source. For the nonuniformly labeled samples, the positions of the chlorin macrocycle originating from C-4 and C-5 of 5-aminolevulinic acid contained >95% C-13 while the remaining positions, which could have originated also from unlabeled acetate, were labeled to similar to 60% with C-13. The 1-D and 2-D MAS data of the labeled chlorosomes, when compared with data on the isolated labeled BChl c aggregated in n-hexane, show that the major component of the MAS signals in the chlorosomes is from BChl c, and only minor signal contributions arise from lipids and proteins. The C-13 MAS signals of the BChl c aggregates were fully assigned by MAS 2-D dipolar correlation spectroscopy, using data on monomeric BChl c in CDCl3/CD3OD as reference. The 2(1)-, 3-, 3(2)-, 5-, 12(1)-, 13-, and 13(1)-carbons are shifted by 2.5 ppm or more upfield with respect to the solution data. The 2-D response of the BChl c in intact chlorosomes is virtually indistinguishable from that of the in vitro aggregate with respect to chemical shifts, line widths, and relative intensities of the cross-peaks. This corroborates previous evidence that self-assembly of BChl c, without the interaction with protein, provides the structural basis for the BChl c organization in vivo.
机译：魔角旋转（MAS）NMR偶极相关光谱法首次应用于生物上完整的系统，即绿色光合细菌淡绿拟南芥（Chlorobium tepidum）的光捕集脂质体。 MAS光谱提供了证据，表明成千上万的细菌叶绿素c（BChl c）分子的自组织是叶绿体的主要结构特征。由以（NaHCO3）-C-13为主要碳源生长的不均匀标记的培养物和以（NaHCO3）-C-13为唯一碳源生长的均一的C-13标记的培养物制备C-13富集的脂质体。对于非均匀标记的样品，源自5-氨基乙酰丙酸的C-4和C-5的二氢卟酚大环的位置包含> 95％的C-13，而其余位置（也可能源自未标记的乙酸盐）被标记为类似于C-13的60％与在正己烷中聚合的分离的标记BChl c的数据比较时，标记的脂质体的一维和二维MAS数据表明，在脂质体中MAS信号的主要成分来自BChl c，并且仅微小的信号贡献来自脂质和蛋白质。使用CDCl3 / CD3OD中单体BChl c的数据作为参考，通过MAS 2-D偶极相关光谱法对BChl c聚集体的C-13 MAS信号进行了完全分配。相对于溶液数据，2（1）-，3-，3（2）-，5-，12（1）-，13-和13（1）碳的位移场偏移量为2.5 ppm或更多。就化学位移，线宽和交叉峰的相对强度而言，完整的脂质体中BChl c的2-D反应与体外聚集体的2-D反应几乎没有区别。这证实了先前的证据，即BChl c的自组装，而没有与蛋白质的相互作用，为体内BChl c的组织提供了结构基础。

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