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Science 28 May 1982:
Vol. 216. no. 4549, pp. 982 - 984
DOI: 10.1126/science.216.4549.982
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Articles

Photoprotection by Carotenoids During Photosynthesis: Motional Dependence of Intramolecular Energy Transfer

ANA L. MOORE 1, ANNA JOY 1, RODERICK TOM 1, DEVENS GUST 1, THOMAS A. MOORE 1, RENÉ V. BENSASSON 2, and EDWARD J. LAND 3

1 Department of Chemistry, Arizona State University, Tempe 85287
2 Laboratoire de Biophysique, INSERM U201, Muséum National d'Histoire Naturelle, 75005 Paris, France
3 Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester M20 9BX, England

A new carotenoporphyrin has been prepared in which a synthetic carotenoid is joined to a tetraarylporphyrin through a flexible trimethylene linkage. This molecule exists primarily in an extended conformation with the carotenoid chromophore far from the porphyrin pgr-electron system. In benzene solution, where large-amplitude molecular motions are rapid, the molecule can momentarily assume less stable conformations which favor triplet energy transfer, and quenching of the porphyrin triplet by the carotenoid is fast. In a polystyrene matrix or frozen glass such motions are slow, and energy transfer cannot compete with other pathways for depopulating the triplet state. These observations help establish the requirements for biological photoprotection.

Submitted on November 9, 1981
Revised on February 10, 1982


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Mimicking Photosynthesis.
D. GUST and T. A. MOORE (1989)
Science 244, 35-41
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