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. 1970 Oct;67(2):813–820. doi: 10.1073/pnas.67.2.813

The π-Cation Radical of Chlorophyll a*

Donald C Borg 1,2,3,4, Jack Fajer 1,2,3,4, Ronald H Felton 1,2,3,4, David Dolphin 1,2,3,4
PMCID: PMC283278  PMID: 16591873

Abstract

Chlorophyll a undergoes reversible one-electron oxidation in dichloromethane and butyronitrile. Removal of the electron by controlled potential electrolysis or by stoichiometric charge transfer to a known cation radical yields a radical (epr line width = 9 gauss, g = 2.0025 ± 0.0001) whose optical spectrum is bleached relative to that of chlorophyll. Upon electrophoresis this bleached species behaves as a cation. By comparison with the known properties of π-cation radicals of porphyrins and chlorins, the chlorophyll radical is also identified as a π-cation. Further correlation of optical and epr properties with published studies on photosynthesis leads to the conclusion that oxidized P700, the first photochemical product of photosystem I in green plants, contains a π-cation radical of the chlorin component of chlorophyll a. This radical is the likely source of the rapidly-decaying, narrow epr signal of 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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