Strouse C E
Department of Chemistry, University of California, Los Angeles, Los Angeles, Calif. 90024.
Proc Natl Acad Sci U S A. 1974 Feb;71(2):325-8. doi: 10.1073/pnas.71.2.325.
Determination of the crystal structure of ethyl chlorophyllide a.2H(2)O by single crystal x-ray diffraction techniques has provided the first detailed molecular structural data available for a magnesium-containing derivative of chlorophyll. At the same time the aggregation observed in this structure serves as the basis for a model of chlorophyll aggregation in vitro and in vivo. The magnesium atom in ethyl chlorophyllide is displaced 0.4 A from the plane of the chlorin ring in the same direction as the methyl ester substituent. A water molecule occupies the fifth coordination site. A second water molecule is hydrogen bonded to the coordinated water molecule and also to the carbonyl oxygen atom of the methyl ester. Hydrogen bonds between the water molecules and carbonyl oxygen atoms link the chlorophyllide molecules into a two-dimensional aggregate of crosslinked one-dimensional polymers. The relationship of this aggregate to aggregates of chlorophyll both in vitro and in vivo is discussed, as is the efficiency of exciton transport within the polymer.
通过单晶X射线衍射技术测定叶绿素酸乙酯a·2H₂O的晶体结构,首次提供了有关含镁叶绿素衍生物的详细分子结构数据。与此同时,在此结构中观察到的聚集作用为体外和体内叶绿素聚集模型奠定了基础。叶绿素酸乙酯中的镁原子在与甲酯取代基相同的方向上,偏离二氢卟吩环平面0.4埃。一个水分子占据第五个配位点。第二个水分子通过氢键与配位水分子相连,同时也与甲酯的羰基氧原子相连。水分子与羰基氧原子之间的氢键将叶绿素酸分子连接成交联的一维聚合物的二维聚集体。本文讨论了这种聚集体与体外和体内叶绿素聚集体的关系,以及聚合物内激子传输的效率。