If you want to make a lasting impression in science, go find a new form of chlorophyll, the light-harvesting protein complexes key to photosynthesis.
Scientists identified the first three forms, chlorophyll a, b and c, in the 19th century. In 1943, 70 years after the discovery of chlorophyll c, Harold Strain and Winston Manning, then at the Carnegie Institution of Washington, described cholorphyll d, which they found in a red algae. (Download a PDF here with subscription)
Move over Strain and Manning. Researchers led by Min Chen at the University of Sydney, Australia are the new kings of chlorophyll. In Science, they report the discovery of chlorophyll f in a cynobacterium found in Australia’s Shark Bay. The newly discovered complex works best in near-infrared light, and it is the most red-shifted chlorophyll yet identified.
Chen’s team went hunting for near infrared-absorbing chlorophyll in stromatolites – matrices of cyanobacteria, calcium carbonate and sediment – because the murky waters above them filter out much of the sunlight.
“I was actually looking for chlorophyll d, which we knew could be found in cyanobacteria living in low light conditions. I thought that stromatolites would be a good place to look, since the bacteria in the middle of the structures don’t get as much light as those on the edge,” Chen said in a press release.
Samuel Beale, a molecular biologist at Brown University, who was not involved in the study, tells Scientific American: “I think what they found here is a new modification of chlorophyll that shows the flexibility of photosynthetic organisms to use whatever light is available.”
Chen’s team grew samples of the Shark Bay stromatolites under near-infrared light. Months later, her team identified chlorophyll f, which best absorbs light at 706 nm – 10 nm shorter than chlorophyll d, which they also found in the culture. Mass spectrometry identified a 906 Dalton molecule whose chemical makeup resembles that of other chlorophylls.
The newly discovered chlorophyll could also be put to use, according to New Scientist. Microbes that produce chlorophyll f could be included in solar cells, along with chlorophylls that capture other parts of the spectrum.
Let’s hope such applications materialize before some lucky chemist discovers the next chlorophyll.
Image: photo by Koala:Bear via Flickr under Creative Commons.