A Red-Shifted Chlorophyll

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Science  19 Aug 2010:
DOI: 10.1126/science.1191127


Chlorophylls are essential for light-harvesting and energy transduction in photosynthesis. Four chemically distinct varieties have been known for the past 60 years. Here, we report isolation of a fifth, which we designate chlorophyll f. Its in vitro absorption (706 nm) and fluorescence (722 nm) maxima are red-shifted compared to all other chlorophylls from oxygenic phototrophs. Based on the optical, mass, and nuclear magnetic resonance spectra, we propose that chlorophyll f is [2-formyl]-chlorophyll a (C55H70O6N4Mg). This finding suggests that oxygenic photosynthesis can be extended further into the infrared region and may open associated bioenergy applications.