An Anomalous Distance Dependence of Intraprotein Chlorophyll-Carotenoid Triplet Energy Transfer
- Kim, Hanyoup
- Dashdorj, Naranbaatar
- Zhang, Huamin
- Yan, Jiusheng
- Cramer, William A.
- Savikhin, Sergei
DOIAbstract
AbstractIn the light-harvesting chlorophyll pigment-proteins of photosynthesis, a carotenoid is typically positioned within a distance of ∼4Å of individual chlorophylls or antenna arrays, allowing rapid triplet energy transfer from chlorophyll to the carotenoid. This triplet energy transfer prevents the formation of toxic singlet oxygen. In the cytochrome b6f complex of oxygenic photosynthesis that contains a single chlorophyll a molecule, this chlorophyll is distant (14Å) from the single β-carotene, as defined by x-ray structures from both a cyanobacterium and a green alga. Despite this separation, rapid (<8ns) long-range triplet energy transfer from the chlorophyll a to β-carotene is documented in this study, in seeming violation of the e...
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