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. 1974 Feb;71(2):325–328. doi: 10.1073/pnas.71.2.325

The Crystal and Molecular Structure of Ethyl Chlorophyllide a·2H2O and Its Relationship to the Structure and Aggregation of Chlorophyll a*

Charles E Strouse 1
PMCID: PMC387996  PMID: 16592136

Abstract

Determination of the crystal structure of ethyl chlorophyllide a·2H2O 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 Å 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.

Keywords: exciton migration, photosynthesis

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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