Small-angle neutron scattering studies of chlorophyll micelles: Models for bacterial antenna chlorophyll.
Small-angle neutron scattering studies of chlorophyll micelles: Models for bacterial antenna chlorophyll.
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叶绿素胶束的小角中子散射研究：细菌天线叶绿素模型。
DOI：
10.1073/pnas.83.11.3791
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发表时间：
1986
影响因子：
11.1
通讯作者：
J. Katz
中科院分区：
文献类型：
--
作者：
D. Worcester;T. J. Michalski;J. Katz
在有机介质中制备的水合叶绿素a（P740）、细菌叶绿素a（P865）、细菌叶绿素c（P750）和脱镁叶绿素a的胶束已经通过小角中子散射进行了研究，以确定它们的形状、尺寸和每单位长度的质量。所有的胶束都是具有明确尺寸的中空圆柱体。P740和P750圆柱体基本上是由水交联的大环化合物的单层，可能在类似于叶绿素衍生物的晶体的排列中。P865胶束更接近于大环的双层。我们表明，形成圆柱体所需的曲率可能是由五坐标叶绿素大环的内禀曲率引起的。研究了P740胶束的形成和另一种亲核试剂吡啶的解聚作用。由于P750胶束的大小和光学光谱几乎相同的杆状结构中观察到的叶绿体，和P865胶束具有非常相似的体内性质的长波长天线的紫色光合细菌的光学性质，我们建议，这些叶绿素的水合圆柱形胶束的功能提供了良好的模型天线叶绿素光合细菌。
Micelles of hydrated chlorophyll a (P740), bacteriochlorophyll a (P865), bacteriochlorophyll c (P750), and pheophytin a prepared in organic media have been studied by small-angle neutron scattering to determine their shape, size, and mass per unit length. All of the micelles are hollow cylinders of well-defined size. The P740 and P750 cylinders are essentially monolayers of macrocycles crosslinked by water, probably in an arrangement similar to that of crystals of chlorophyll derivatives. The P865 micelle is more nearly a bilayer of macrocycles. We show that the curvature necessary to form cylinders probably results from intrinsic curvature of the five-coordinated chlorophyll macrocycle. Studies of P740 micelle formation and the disaggregating effects of another nucleophile (pyridine) are described. As the P750 micelles are nearly identical in size and optical spectra to the rod-shaped structures observed in chlorosomes, and the P865 micelles have optical properties very similar to the in vivo properties of the long-wavelength antenna of purple photosynthetic bacteria, we propose that features of the hydrated cylindrical micelles of these chlorophylls provide good models for antenna chlorophyll in photosynthetic bacteria.